Detergent-free and low-ash lubricating composition

Abstract

The present disclosure describes detergent-free and low ash lubricating compositions that achieve piston cleanliness using one or more succinimide dispersants, one or more ash-free antiwear additives, and one or more antioxidants while maintaining a selected ratio of sulfur, phosphorus, and nitrogen.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. application No. 18 / 068,795, filed on December 20, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to detergent-free and low-ash additive systems and lubricating compositions containing the additive systems, which are configured to improve piston cleanliness. Background Art

[0004] Automakers continue to push for improved efficiency and fuel economy, and as a result, the demand for engines, lubricants, and their components continues to increase. In some cases, this continued push for fuel economy improvements has shifted the automotive market towards direct injection gasoline (DIG) engines; however, one of the drawbacks of DIG technology is the potential increase in exhaust particulates, and in particular, increased levels of soot and / or ash. One option to mitigate the increase in soot and / or ash is to use a gasoline particulate filter (GPF) to remove such particulates from the exhaust, but such use is not without trade-offs. Although in some cases, a fouled GPF can be regenerated by burning off collected soot particles, the GPF is typically unable to clear the collected ash levels, which are often the result of burning a small amount of engine oil in the combustion chamber, and therefore the GPF may have a limited lifespan. Alternatively, it is often desirable to simply reduce the soot and / or ash contribution level of the lubricant, but reducing these contributing factors while still meeting the high demands of manufacturer and industry performance standards is often challenging. While lower ash contributing components in a lubricant may be desirable, in many cases reducing ash contributing components (such as detergents and / or anti-wear additives) tends to reduce other performance characteristics of the lubricant.

[0005] The ash-containing components in engine oils are usually specified by sulfated ash (SASH) limits. Engine oils usually have a SASH limit of up to 1% by weight. However, formulating engine oils to meet lower SASH limits (such as less than 0.2% by weight) is usually challenging because when some major ash-contributing substances are removed from engine oils, the performance of the oil decreases. In particular, calcium, magnesium, sodium and / or lithium are examples of the main ash-contributing metals provided in the detergent additives usually used in engine oils. Detergent additives are usually included in engine oils because they can clean metal surfaces, such as pistons. It is believed that detergents work by acting as surfactants that can remove deposits from metal surfaces, but in order to achieve this function, detergents usually need to be metal salts, and therefore also contribute a certain level of ash to the lubricant to play its intended function. Therefore, limiting these main ash-contributing substances in engine oils to achieve lower SASH targets will also tend to limit the ability of low-ash engine oils in achieving acceptable piston cleanliness levels. Summary of the Invention

[0006] In one method or embodiment, a detergent-free, low-ash lubricating composition (such as those defined herein) is described that provides good piston cleanliness. In one aspect, the composition comprises: one or more base oils of lubricating viscosity; a total sulfated ash (SASH) less than about 0.2 wt. % as measured by ASTM D874; one or more succinimide dispersants derived from polyisobutylene having a number average molecular weight of at least about 1000, wherein each of the succinimide dispersants has up to about 2 wt. % nitrogen, and wherein at least one of the succinimide dispersants is post-treated with a boron compound; one or more ashless anti-wear additives; and one or more antioxidants. In other aspects, the composition further has: a total base number (TBN) of at least about 4 according to ASTM D2896; at least about 1000 ppm nitrogen, no more than 100 ppm boron, no more than 800 ppm sulfur, and a sulfur-to-phosphorus ratio of 2.0 or less, and a nitrogen-TBN ratio of about 150 or greater; and wherein the detergent-free, low-ash lubricating composition is substantially free of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium. In other aspects, in the context of the present disclosure, substantially free means that the detergent-free, low-ash lubricating composition herein further has less than about 10 ppm of each of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium.

[0007] In other embodiments, the composition of the preceding paragraph may have other features or embodiments in any combination. These other features or embodiments may include one or more of the following: further comprising no more than about 500 ppm phosphorus and no more than about 600 ppm sulfur; and / or wherein the composition comprises at least about 6 times more antioxidant than the one or more ashless antiwear additives; and / or wherein the total sulfated ash (SASH) measured according to ASTM D874 is less than 0.1 wt %; and / or wherein the one or more ashless antiwear additives comprise one or more ashless dialkyl dithiophosphate antiwear additives; and / or wherein the one or more ashless dialkyl dithiophosphate antiwear additives have a structure of Formula I or a salt thereof:

[0008]

[0009] wherein R4 and R5 are independently C3 to C8 linear or branched alkyl groups, and R6 is -H or -CH3; and / or wherein the one or more antioxidants comprise an aminic antioxidant, a hindered phenolic antioxidant, or a combination thereof; and / or wherein the aminic antioxidant is selected from an aromatic amine, an alkylated diphenylamine, an alkyldiphenylamine, a dialkyldiphenylamine, an octyldiphenylamine, a dioctyldiphenylamine, a phenyl-α-naphthylamine, an alkylated phenyl-α-naphthylamine, a hindered non-aromatic amine, or a combination thereof; and / or wherein the one or more succinimide dispersants comprise: (i) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 1000 to about 2000 and post-treated with a boron compound; (ii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight greater than about 2000; and (iii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of 1000 to about 2000; and / or and / or wherein greater than 50 weight percent of the total nitrogen is provided by one or more antioxidants; and / or further comprising a dispersant olefin copolymer viscosity index improver comprising the reaction product of an acylated olefin copolymer and a polyamine, wherein the acylated olefin copolymer comprises an olefin copolymer having grafted thereon from about 0.3 to about 0.75 carboxyl groups per 1000 number average molecular weight units of the olefin copolymer, wherein the olefin copolymer has a number average molecular weight of from about 40,000 to about 150,000, and wherein the polyamine is an N-arylphenylenediamine; and / or wherein the lubricating composition comprises from about 1 weight percent to about 4 weight percent of the dispersant olefin copolymer viscosity index improver; and / or wherein the total amount of nitrogen, sulfur, and phosphorus relative to the amount of boron (N+S+P) / B is from about 20 to about 50; and / or wherein the lubricating composition is tested according to the "Sequence IIIH Engine Test" (ASTM D8111) cleans piston deposits with a merit rating of at least about 4 total weighted piston deposits, and wherein the lubricating composition exhibits an average engine clear coat (AES) of at least 8 merit and / or an average engine sludge rating of at least 7.6 merit according to the "Sequence VH Test" (ASTM D8256).

[0010] In other methods or embodiments, the present disclosure also provides a method for lubricating a combustion engine using a detergent-free, low-ash lubricating composition (such as those components defined herein). In various aspects, the methods herein include: lubricating a combustion engine using a detergent-free, low-ash lubricating composition; wherein the detergent-free, low-ash lubricating composition comprises one or more base oils of lubricating viscosity; a total sulfated ash (SASH) less than about 0.2 wt. % as measured by ASTM D874; one or more succinimide dispersants derived from polyisobutylene having a number average molecular weight of at least about 1000, wherein each of the succinimide dispersants has up to about 2 wt. % nitrogen, and wherein at least one of the succinimide dispersants is post-treated with a boron compound; one or more ash-free anti-wear additives; one or more antioxidants; a total base number (TBN) as measured by ASTM D874. The present invention also provides a method for lubricating a lubricant composition comprising: a D2896 of at least about 4; at least about 1000 ppm nitrogen, no more than 100 ppm boron, no more than 800 ppm sulfur, and a sulfur-to-phosphorus ratio of 2.0 or less, and a nitrogen-to-TBN ratio of about 150 or greater; and wherein the detergent-free, low-ash lubricating composition is substantially free of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium. In other aspects, the lubrication method utilizing the lubricating composition herein cleans piston deposits according to the "Sequence IIIH Engine Test" (ASTM D8111) with a merit rating of at least about 4 total weighted piston deposits, and wherein the lubricating composition exhibits an average engine varnish (AES) of at least 8 merits and / or an average engine sludge grade of at least 7.6 merits according to the "Sequence VH Test" (ASTM D8256).

[0011] In other methods or embodiments, the methods described in the previous paragraphs may include other features, method steps or embodiments in any combination. These other features, method steps or embodiments may include one or more of the following: wherein the composition further comprises less than about 10 ppm of each of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc and potassium; and / or further comprises no more than about 500 ppm of phosphorus and no more than about 600 ppm of sulfur; and / or wherein the composition comprises at least about 6 times more of the one or more antioxidants relative to the one or more ashless antiwear additives; and / or wherein the total sulfated ash (SASH) measured according to ASTM D874 is less than about 0.1 wt%; and / or wherein the one or more ashless antiwear additives comprise one or more ashless dialkyl dithiophosphate antiwear additives; and / or wherein the one or more ashless dialkyl dithiophosphate antiwear additives have the structure of Formula I or a salt thereof:

[0012]

[0013] wherein R4 and R5 are independently C3 to C8 linear or branched alkyl groups, and R6 is -H or -CH3; and / or wherein the one or more antioxidants comprise an aminic antioxidant, a hindered phenolic antioxidant, or a combination thereof; and / or wherein the aminic antioxidant is selected from aromatic amines, alkylated diphenylamines, alkyldiphenylamines, dialkyldiphenylamines, octyldiphenylamines, dioctyldiphenylamines, phenyl-α-naphthylamines, alkylated phenyl-α-naphthylamines, hindered non-aromatic amines, or a combination thereof; and / or wherein the one or more succinimide dispersants comprise: (i) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 1000 to about 2000 and post-treated with a boron compound; (ii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight greater than about 2000; and (iii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 1000 to about 2000. and / or wherein greater than 50 weight percent of the total nitrogen is provided by one or more antioxidants; and / or further comprising a dispersant olefin copolymer viscosity index improver comprising a reaction product of an acylated olefin copolymer and a polyamine, wherein the acylated olefin copolymer comprises an olefin copolymer having from about 0.3 to about 0.75 carboxyl groups grafted thereon per 1000 number average molecular weight units of the olefin copolymer, wherein the olefin copolymer has a number average molecular weight of from about 40,000 to about 150,000, and wherein the polyamine is an N-arylphenylenediamine; and / or wherein the lubricating composition comprises from about 1 weight percent to about 4 weight percent of the dispersant olefin copolymer viscosity index improver; and / or wherein the total amount of nitrogen, sulfur, and phosphorus relative to the amount of boron (N+S+P) / B is from about 20 to about 50.

[0014] In other methods or embodiments, the present disclosure describes using any embodiment of the detergent-free and low-ash lubricating composition of the present disclosure to clean piston deposits and achieve a total weighted piston deposit rating of at least about 4 according to the "Sequence IIIH Engine Test" (ASTM D8111), and / or achieve an average engine varnish (AES) of at least 8 according to the "Sequence VH Test" (ASTM D8256) and / or achieve an average engine sludge rating of at least 7.6.

[0015] In the method of use described in the preceding paragraph, the detergent-free, low-ash lubricating composition (such as those defined herein) comprises any embodiment of the present disclosure and specifically comprises: one or more base oils of lubricating viscosity; a total sulfated ash (SASH) of less than about 0.2 wt. % as measured by ASTM D874; one or more succinimide dispersants derived from polyisobutylene having a number average molecular weight of at least about 1000, wherein each of the succinimide dispersants has up to about 2 wt. % nitrogen, and wherein at least one of the succinimide dispersants is post-treated with a boron compound; one or more ashless antiwear additives; and one or more antioxidants. In other aspects, the composition further has: a total base number (TBN) of at least about 4 according to ASTM D2896; at least about 1000 ppm nitrogen, no more than 100 ppm boron, no more than 800 ppm sulfur, and a sulfur-to-phosphorus ratio of 2.0 or less, and a nitrogen-TBN ratio of about 150 or greater; and wherein the detergent-free, low-ash lubricating composition is substantially free of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium. In other aspects, in the context of the uses of the present disclosure, substantially free means that the detergent-free and low-ash lubricating composition herein further has less than about 10 ppm of each of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium.

[0016] Additional details and advantages of the present disclosure will be partially set forth in the following description and / or may be learned by practicing the present disclosure. The details and advantages of the present disclosure may be realized and obtained by the elements and combinations specifically noted in the appended claims. It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory and do not limit the present disclosure as claimed. DETAILED DESCRIPTION

[0017] Sulfated ash is a measure of the total weight percentage of ash in a lubricating oil composition. Sulfated ash measurement of a lubricating oil composition is related to the total metal content therein and can be conveniently measured according to ASTM D874 and / or other commonly used evaluation methods known in the art and as described herein. In one aspect, the present disclosure describes low-ash additives and lubricants containing such additives that provide extremely low sulfated ash (SASH) content in a lubricating oil composition, with a sulfated ash content of about 0.2% by weight or less, about 0.1% by weight or less, about 0.08% by weight or less, about 0.06% by weight or less, or about 0.05% by weight or less. In another aspect, the present disclosure also describes additives and lubricants that are also free of detergent additives and therefore free of the metals provided by detergents. As used herein, the detergent-free and low-ash lubricating compositions herein not only have the above-mentioned low SASH levels, but also are free of detergent, meaning that the compositions are free of detergent metals, including calcium, magnesium, sodium, and lithium. In addition, the compositions herein are also free of barium, copper, lead, molybdenum, zinc, and potassium, which are other ash-contributing elements. As used herein, "free" in the context of detergents and / or the metals and minerals means that the compositions herein have about 10 ppm or less, about 5 ppm or less, about 2 ppm or less, about 1 ppm or less of each element, metal, or mineral (e.g., calcium, magnesium, sodium, lithium, barium, copper, lead, molybdenum, zinc, and / or potassium), or no detectable amount of such elements, metals, or minerals in the composition. Even without conventional detergent additives and the associated metal salts from those detergents acting as surfactants, the compositions herein surprisingly achieve the desired level of piston cleanliness by carefully selecting the elemental relationships of the remaining components in the composition.

[0018] Turning to more detail, and in some embodiments, the detergent-free, low-ash lubricating compositions herein comprise: at least one or more base oils of lubricating viscosity; a total sulfated ash (SASH) of less than about 0.2 wt. % as measured by ASTM D874; one or more succinimide dispersants derived from polyisobutylene having a number average molecular weight of at least about 1000, wherein each of the succinimide dispersants has up to about 2 wt. % nitrogen, and wherein (if more than one is included) at least one of the succinimide dispersants is post-treated with a boron compound; one or more ashless antiwear additives; one or more antioxidants; a total base number (TBN) as measured by ASTM D874. The detergent-free, low-ash lubricating composition comprises a D2896 of at least about 4; at least about 1000 ppm nitrogen, no more than 100 ppm boron, no more than 800 ppm sulfur, a sulfur-to-phosphorus ratio of 2.0 or less, and a nitrogen-to-TBN ratio of about 150 or greater; and wherein the detergent-free, low-ash lubricating composition does not contain calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and / or potassium as defined above. In other embodiments, the detergent-free, low-ash lubricating composition further comprises a weight ratio of the total nitrogen, total sulfur, and total phosphorus to the total boron (N+S+P) / B of about 20 to about 50.

[0019] In other embodiments, the detergent-free, low-ash lubricating compositions herein may have limited amounts of phosphorus, sulfur, and certain relationships of antioxidants to anti-wear additives. For example, the detergent-free, low-ash lubricants herein may also have no more than about 500 ppm of phosphorus, no more than about 600 ppm of sulfur, and / or may also have at least about 6 times more of one or more antioxidants relative to one or more ash-free anti-wear additives.

[0020] As shown in the examples below, such embodiments of the detergent-free, low-ash lubricating compositions herein are effective in cleaning piston deposits even without the use of conventional detergent additives, with a Total Weighted Piston Deposits rating of at least about 4 out of 5 when measured according to the "Sequence IIIH Engine Test" (ASTM D8111), and / or embodiments of the detergent-free, low-ash lubricating compositions herein also exhibit an Average Engine Clearcoat (AES) rating of at least 8 out of 5 and / or an Average Engine Sludge Rating of at least 7.6 out of 5 according to the "Sequence VH Test" (ASTM D8256).

[0021] Ashless anti-wear additives

[0022] In methods or embodiments, the detergent-free and low-ash lubricating compositions herein comprise one or more ash-free antiwear additives in the form of acidic thiophosphates or thiophosphate esters, such as ash-free, amine-free dialkyl dithiophosphates or sulfur-containing phosphate esters. In embodiments, the one or more ash-free antiwear additives provide the lubricating composition with about 100 ppm to about 500 ppm of antiwear phosphorus, in other methods, about 150 ppm to about 450 ppm of antiwear phosphorus, in other methods, about 200 ppm to about 400 ppm of antiwear phosphorus, or in other methods, about 300 ppm to about 390 ppm of antiwear phosphorus. In alternative methods, the detergent-free and low-ash lubricating compositions herein comprise about 0.1 wt % to about 0.5 wt % of one or more ash-free antiwear additives, in other methods, about 0.2 wt % to about 0.48 wt %, in other methods, or about 0.3 wt % to about 0.45 wt % of one or more ash-free antiwear additives. Since the compositions herein are preferably free of conventional ZDDP additives (i.e., such as, in some embodiments, about 10 ppm or less of zinc from ZDDP, or no detectable amounts of ZDDP additives), the detergent-free and low-ash lubricating compositions herein also preferably comprise 80 wt % to 100 wt %, more preferably 90 wt % to 100 wt %, and most preferably all of the phosphorus and / or sulfur in the lubricant provided by the ashless antiwear additive.

[0023] In some embodiments, the one or more ashless anti-wear additives herein are acidic thiophosphates, thiophosphate esters, or sulfur-containing phosphate esters and may have one or more sulfur-phosphorus bonds. The thiophosphate ester may be a dithiophosphate ester. In a more specific method, the acidic thiophosphate or thiophosphate ester may have a structure of Formula I or a salt thereof

[0024]

[0025] wherein R4 and R5 are each independently a linear or branched C1 to C10 hydrocarbon group, and each R7 is a C1 to C10 linear or branched carboxyl group or a C1 to C10 linear or branched alkanoate alkyl ester group. Preferably, R4 and R5 are each a C3 to C8 linear or branched alkyl group and R7 is derived from 2-methylpropionic acid, such that the second phosphorus product (or its salt) has the structure of Formula Ia below:

[0026]

[0027] wherein R4 and R5 are independently C3 to C8 linear or branched alkyl groups (preferably branched C4 groups), and R6 is -H or -CH3. In some methods or embodiments, the one or more ashless antiwear additives include at least 3-[[bis(2-methylpropoxy)thiophosphono]thio]-2-methylpropionic acid.

[0028] antioxidants

[0029] In other methods or embodiments, the detergent-free and low-ash lubricating compositions herein further comprise one or more antioxidants, preferably selected from aminic antioxidants, hindered phenolic antioxidants, or combinations thereof. As noted above, embodiments herein may include about 6 times the amount of one or more antioxidants relative to the one or more ash-free anti-wear additives to achieve the desired piston cleanliness with the detergent-free and low-ash lubricant.

[0030] In one method or embodiment, the aminic antioxidant may include, but is not limited to, an antioxidant selected from aromatic amines, alkylated diphenylamines, phenyl-α-naphthylamines, alkylated phenyl-α-naphthylamines, hindered non-aromatic amines, and the like, or combinations thereof. The total amount of aminic antioxidant in the detergent-free, low-ash lubricating composition herein is an amount that delivers the following antioxidant nitrogen: at least about 650 ppm antioxidant nitrogen, and in some methods, about 670 ppm to about 800 ppm antioxidant nitrogen, in other methods, about 690 ppm to about 750 ppm antioxidant nitrogen, or in other methods, about up to about 700 ppm antioxidant nitrogen. In other methods, the detergent-free, low-ash lubricating composition herein may contain up to about 3 wt% aminic antioxidant, or about 1 wt% to about 3 wt% aminic antioxidant. In some approaches, the nitrogen from the aminic antioxidant contributes at least half of the nitrogen in the lubricant, and for example, contributes at least about 50 weight percent of the total nitrogen in the detergent-free, low-ash lubricant, and in other approaches, contributes from about 50 weight percent to about 60 weight percent of the total nitrogen in the detergent-free, low-ash lubricant composition.

[0031] In some methods, the amine antioxidant may be one or more aromatic amine antioxidants, and may include, but is not limited to, diarylamines having the formula:

[0032]

[0033] wherein R′ and R″ each independently represent a substituted or unsubstituted aryl group having from 6 to 30 carbon atoms. If substituted, suitable substituents for the aryl groups of R′ and R″ include aliphatic hydrocarbon groups such as alkyl groups having from 1 to 30 carbon atoms, a hydroxyl group, a halogen group, a carboxylic acid or ester group, or a nitro group. The aryl group may be a substituted or unsubstituted phenyl or naphthyl group, in particular wherein one or both of these aryl groups are substituted with at least one alkyl group having from 4 to 30 carbon atoms, preferably from 4 to 18 carbon atoms, most preferably from 4 to 9 carbon atoms. In the process, one or both aryl groups may be substituted, for example with monoalkylated diphenylamine, dialkylated diphenylamine, C9 alkylated diphenylamine, or a mixture of monoalkylated and dialkylated diphenylamines.

[0034] Examples of diarylamine antioxidants that can be used include, but are not limited to, diphenylamine; various alkylated diphenylamines, 3-hydroxydiphenylamine, N-phenyl-1,2-phenylenediamine, N-phenyl-1,4-phenylenediamine, monobutyldiphenylamine, dibutyldiphenylamine, monooctyldiphenylamine, dioctyldiphenylamine, monononyldiphenylamine, dinonyldiphenylamine, monotetradecyldiphenylamine, tetracosyldiphenylamine, phenyl-α-naphthylamine, monooctylbenzene-α-naphthylamine, phenyl-β-naphthylamine, monoheptyldiphenylamine, diheptyldiphenylamine, para-oriented styrenated diphenylamine, mixed butyloctyldiphenylamine, and mixed octylstyryldiphenylamine.

[0035] Suitable hindered phenol antioxidants may contain sec-butyl and / or t-butyl groups as sterically hindered groups. The phenolic groups may also be substituted with hydrocarbyl groups and / or bridging groups connected to a second aromatic group. Examples of suitable hindered phenol antioxidants include 2,6-di-t-butylphenol, 4-methyl-2,6-di-t-butylphenol, 4-ethyl-2,6-di-t-butylphenol, 4-propyl-2,6-di-t-butylphenol or 4-butyl-2,6-di-t-butylphenol, or 4-dodecyl-2,6-di-t-butylphenol. In one embodiment, the hindered phenol antioxidant may be an ester and may include, for example, Irganox®, available from BASF. TM L-135 or an addition product derived from 2,6-di-tert-butylphenol and an alkyl acrylate, wherein the alkyl group may contain from about 1 to about 18, or from about 2 to about 12, or from about 2 to about 8, or from about 2 to about 6, or about 4 carbon atoms. Another commercially available hindered phenol antioxidant may be an ester and may include Ethanox ® available from Albemarle Corporation. TM 4716.

[0036] In some embodiments, the detergent-free, low-ash lubricating compositions herein may also include from about 0.5 wt % to about 1 wt % of a hindered phenolic antioxidant, and in other embodiments, from about 0.5 wt % to about 0.8 wt % of a hindered phenolic antioxidant. Preferably, when the detergent-free, low-ash lubricating composition includes both an aminic antioxidant and a hindered phenolic antioxidant, the composition has at least about 3 times as much aminic antioxidant (based on weight) as hindered phenolic antioxidant, and preferably from about 3 times to about 4 times as much aminic antioxidant (based on weight) as hindered phenolic antioxidant.

[0037] One or more succinimide dispersants

[0038] The detergent-free, low-ash lubricating compositions herein also include a dispersant system comprising one or more succinimide dispersants derived from polyisobutylene having a number average molecular weight of at least about 1000, and when more than one succinimide dispersant is included, at least one dispersant in the system is post-treated with a boron compound. In embodiments, less than half of the lubricant nitrogen is provided by the dispersant, and preferably, from about 40% to less than 50% of the lubricant nitrogen is provided by the one or more succinimide dispersants. In the method, the succinimide dispersant provides from about 600 ppm to less than about 700 ppm of nitrogen to the lubricant herein.

[0039] In one approach, the one or more succinimide dispersants include: (i) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 1000 to less than about 2000 that has been post-treated with a boron compound; (ii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of greater than about 2000 that has not been post-treated with boron; and (iii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of 1000 to about 2000 that has not been post-treated with a boron compound.

[0040] Succinimide dispersants are often referred to as ashless dispersants because they do not contain ash-forming metals before being mixed into the lubricating composition and generally do not contribute any ash when added to the lubricant. Ashless dispersants are characterized by polar groups attached to relatively high molecular weight hydrocarbon chains. Typical ashless dispersants include N-substituted long chain alkenyl succinimides. Examples of nitrogen-substituted long chain alkenyl succinimides include polyisobutylene succinimides, wherein the number average molecular weight of the polyisobutylene substituent is in the range of about 1,000 to about 50,000, or to about 5,000, or to about 3,000, or to about 2,000 to about 3,000, as measured by GPC. Succinimide dispersants and their preparation are disclosed, for example, in US Pat. No. 7,897,696 and US Pat. No. 4,234,435, which are incorporated herein by reference. The alkenyl substituent can be prepared from polymerizable monomers containing from about 2 to about 16, or from about 2 to about 8, or from about 2 to about 6 carbon atoms.Succinimide dispersants are typically imides formed from polyamines, typically poly(ethyleneamine).

[0041] In the method, the preferred amine for the dispersant of the present invention can be selected from polyamines and hydroxylamines. Examples of polyamines that can be used include, but are not limited to, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA) and higher homologues such as pentaethylenehexamine (PEHA) and the like. In some methods, so-called heavy polyamines can be used, which are mixtures of polyalkylene polyamines containing small amounts of low-order polyamine oligomers such as TEPA and PEHA (pentaethylenehexamine) but primarily having 6 or more nitrogen atoms per molecule, 2 or more primary amines and oligomers that are more extensively branched than conventional polyamine mixtures. Heavy polyamines preferably include polyamine oligomers containing 7 or more nitrogen atoms per molecule and 2 or more primary amines per molecule.

[0042] In some embodiments, polyisobutylene (PIB) is a preferred reactant for forming the dispersant when included in the dispersant herein and may have a terminal double bond content greater than 50 mol%, greater than 60 mol%, greater than 70 mol%, greater than 80 mol%, or greater than 90 mol%. Such PIBs are also referred to as highly reactive PIBs ("HR-PIBs"). HR-PIBs having a number average molecular weight in the range of about 800 to about 5000 as determined by GPC are suitable for use in embodiments of the present disclosure. Conventional PIBs typically have a terminal double bond content of less than 50 mol%, less than 40 mol%, less than 30 mol%, less than 20 mol%, or less than 10 mol%.

[0043] As determined by GPC, HR-PIB having a number average molecular weight in the range of about 1,000 to about 3,000 (or preferably about 1,200 to about 3,000 or in the above range) may be suitable. Such HR-PIB is commercially available or can be synthesized by polymerization of isobutylene in the presence of a non-chlorinated catalyst, such as boron trifluoride, as described in US 4,152,499 and US 5,739,355. When used in the aforementioned thermal olefin reaction, HR-PIB can increase the conversion rate in the reaction and reduce the amount of sediment formation due to enhanced reactivity. Suitable methods are described in US Pat. No. 7,897,696. In one embodiment, the present disclosure also includes at least one dispersant derived from polyisobutylene succinic anhydride ("PIBSA"). PIBSA can have an average of about 1.0 to about 2.0 succinic acid moieties per polymer.

[0044] In some methods, some dispersants in the detergent-free and low-ash lubricating compositions herein may be free of any post-treatment, such as post-treatment with boron, urea, thiourea, dimercaptothiadiazole, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, maleic anhydride, nitriles, epoxides, carbonates, cyclic carbonates, hindered phenolic esters, and phosphorus compounds. In other embodiments, at least one dispersant in the detergent-free and low-ash lubricating compositions herein may be post-treated by conventional methods by reacting with any of a variety of post-treatment agents. In one method, at least one dispersant in the composition herein may be post-treated with a boron compound. Suitable post-treatment agents include boron, urea, thiourea, dimercaptothiadiazole, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, maleic anhydride, nitriles, epoxides, carbonates, cyclic carbonates, hindered phenolic esters, and phosphorus compounds. (See, e.g., U.S. Pat. Nos. 7,645,726; 7,214,649; 8,048,831; and 5,241,003, which are incorporated herein by reference in their entireties.)

[0045] If post-treated with boron, the boron compound used as the post-treatment agent can be selected from boron oxide, boron halides, boric acid, and boric acid esters in an amount to provide from about 0.1 atomic percent boron per mole of nitrogen composition to about 20 atomic percent boron per atomic percent of nitrogen used. The dispersant post-treated with boron can contain from about 0.05 weight percent to about 2.0 weight percent boron, or in other approaches, from about 0.05 weight percent to about 0.7 weight percent boron, based on the total weight of the borated dispersant.

[0046] In other methods and if used, a carboxylic acid can be used as a post-treatment agent and can be a saturated or unsaturated monocarboxylic acid, dicarboxylic acid, or polycarboxylic acid. Examples of carboxylic acids include, but are not limited to, maleic acid, fumaric acid, succinic acid, and naphthalene dicarboxylic acid (e.g., 1,8-naphthalene dicarboxylic acid). An anhydride can be used as a post-treatment agent and can be selected from monounsaturated anhydrides (e.g., maleic anhydride), alkyl or alkylene substituted cyclic anhydrides (e.g., succinic anhydride or glutamic anhydride), and aromatic carboxylic anhydrides (including naphthalene dicarboxylic anhydride, e.g., 1,8-naphthalene dicarboxylic anhydride).

[0047] In one embodiment, and if used, the method of post-treating the dispersant comprises first forming a succinimide product as described above, and then further reacting the succinimide product with a post-treating agent such as a boron compound (e.g., boric acid). In some cases, the dispersant herein can be post-treated with more than one post-treating agent. For example, the dispersant can be post-treated with a boron compound (such as boric acid) and an anhydride (such as maleic anhydride and / or 1,8-naphthalic anhydride).

[0048] In embodiments, the detergent-free and low-ash lubricating compositions herein may comprise at least about 5 wt % of one or more dispersants herein or about 5 wt % to about 15 wt %, preferably about 5 wt % to about 10 wt %, or more preferably about 5 wt % to about 8 wt % of one or more dispersants as described herein.

[0049] Low ash composition

[0050] As noted above, the detergent-free, low-ash lubricant compositions herein are formulated to have extremely low levels of sulfated ash and include an additive package that provides a composition having a sulfated ash level (ASTM D874) of about 0.2 wt % or less, about 0.1 wt % or less, about 0.08 wt % or less, about 0.06 wt % or less, or about 0.05 wt % or less (ASTM D874). In other approaches, the lubricant compositions herein may also include about 0.01 wt % or more sulfated ash, about 0.02 wt % or more, about 0.3 wt % or more, or about 0.04 wt % or more sulfated ash (ASTM D874).

[0051] As used herein, "sulfated ash" or "SASH" refers to the amount of sulfated ash measured using ASTM D874. Alternatively, sulfated ash can also be calculated based on the amount of metals in the lubricant. For example, sulfated ash (SASH) can optionally be calculated based on the total metal elements that contribute to the SASH in the lubricant composition, adjusted by a factor for each metal type. Metals that contribute to SASH include (along with the adjustment factors) barium (1.7), boron (3.22), calcium (3.4), copper (1.252), lead (1.464), lithium (7.92), magnesium (4.95), manganese (1.291), molybdenum (1.5), potassium (2.33), sodium (3.09), and zinc (1.5). Specifically, the ppmw content of each of the metal elements present in the lubricating oil composition that are believed to contribute to sulfated ash is multiplied by its corresponding factor as described above; then, the products of each metal element / factor adjustment are added together, and the sum is divided by 10,000 to calculate the weight percent of SASH in the lubricating composition. Unless otherwise specified, all sulfated ash levels herein are measured using ASTM D874.

[0052] To achieve such low levels of sulfated ash, the lubricant compositions herein have a selected additive package that provides an additive mixture that is free of detergent additives (as described and defined above), thereby providing virtually no calcium, magnesium, lithium, sodium, and other detergent metals, and only providing lower or selected amounts of other compounds that provide boron, molybdenum, and / or zinc. To this end, the lubricants herein preferably include an additive that provides no more than about 100 ppm of boron (preferably no more than about 90 ppm of boron or no more than about 80 ppm of boron) and 10 ppm or less of each of calcium, barium, copper, lead, lithium, magnesium, zinc, sodium, molybdenum, and / or combinations thereof. In other approaches, the lubricating compositions herein are substantially free of metallic detergents, and more preferably, the lubricating compositions have metallic detergents that provide less than about 10 ppm of a single and / or total detergent metal, less than 8 ppm of a single or total detergent metal, less than 5 ppm of a single or total detergent metal, less than 2 ppm of a single or total detergent metal, less than 1 ppm of a single or total detergent metal, or no detectable amount of detergent metal, wherein the detergent metal is selected from calcium, magnesium, sodium, lithium, etc. In other approaches, the lubricating oil compositions herein are also substantially free of metal dialkyl dithiophosphates, such as zinc dialkyl dithiophosphates, and in such cases, preferably have about 10 ppm or less of zinc provided by such metal dialkyl dithiophosphates.

[0053] In other embodiments, the detergent-free, low-ash lubricating composition also maintains a weight ratio of total sulfur to total phosphorus of less than about 2.0, and preferably from about 1.0 to about 1.8. As noted above, the phosphorus and sulfur are provided by the ashless antiwear additive.

[0054] In other embodiments, the detergent-free, low ash lubricating compositions herein have a total base number (TBN) of at least about 4 mg KOH / g (in other embodiments, from about 4 mg KOH / g to about 10 mg KOH / g, and in yet other embodiments, from about 4 mg KOH / g to about 6 mg KOH / g) as measured according to ASTM D2898.

[0055] Among other approaches, the detergent-free and low-ash lubricating compositions herein have a unique relationship between the total amount of nitrogen relative to the TBN of the composition. For example, the compositions herein may have the following nitrogen to TBN ratio: greater than 150 ppm / mg KOHg -1 , in other methods, with about 200 ppm / mg KOHg -1 to about 350ppm / mg KOHg -1 , and in other methods, with about 280 ppm / mg KOHg -1 to about 325ppm / mg KOHg -1 An example of calculating this ratio is provided in the Examples herein.

[0056] In additional methods or embodiments, the detergent-free and low-ash lubricating compositions herein may also have elemental relationships between the total amounts of nitrogen, sulfur, phosphorus, and boron that are uniquely found to affect piston cleanliness when the lubricating composition is detergent-free and low-ash, such as those characteristics described above. For example, in one embodiment, the detergent-free and low-ash lubricating composition may have a weight ratio of total nitrogen, total sulfur, and total phosphorus to total boron (i.e., (N+S+P) / B) of about 20 to about 50, and more preferably about 22 to about 30, to facilitate piston cleanliness achieved with low metal and ash contents as described herein.

[0057] Lubricating oil composition

[0058] The additives herein are combined with a major amount of a base oil or base oil blend of lubricating viscosity (as described below) in combination with one or more additional optional additives to produce a lubricating oil composition. In the methods, the lubricating oil composition comprises about 50% by weight or more of the base oil blend, about 60% by weight or more, about 70% by weight or more, or about 80% by weight or more to about 95% by weight or less, about 90% by weight or less, about 85% by weight or less of the base oil blend, such blends being discussed further below. The lubricating composition herein may have a KV100 of about 2 cSt to about 15 cSt (ASTM D445), preferably about 5 cSt to about 12 cSt, and more preferably 5 cSt to about 10 cSt.

[0059] When the detergent-free and low-ash lubricating compositions herein are combined with the indicated component and element relationships, the lubricating compositions herein can achieve the desired level of piston cleanliness even without the use of conventional detergent additives. As noted above, embodiments of the lubricating compositions herein clean piston deposits according to the "Sequence IIIH Engine Test" (ASTM D8111) with an advantage rating of at least about 4 total weighted piston deposits (where a higher rating means the piston is cleaner at the end of the test), and embodiments of the lubricating compositions herein also exhibit an average engine varnish (AES) rating of at least 8 advantages and / or an average engine sludge rating of at least 7.6 advantages according to the "Sequence VH Test" (ASTM D8256).

[0060] Base oil blends The base oil used in the detergent-free, low-ash lubricating oil composition herein can be an oil of lubricating viscosity and is selected from any one of Group I to Group V base oils as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. The five groups of base oils are as follows:

[0061] Table 1

[0062]

[0063] Class I, Class II and Class III are mineral oil processed raw materials.Class IV base oil contains real synthetic molecular substances, and these synthetic molecular substances are produced by the polymerization of olefinically unsaturated hydrocarbons.Many Class V base oils are also real synthetic products, and can comprise diester, polyol ester, polyalkylene glycol, alkylated aromatic compound, polyphosphate ester, polyvinyl ether and / or polyphenylene ether etc., but can also be naturally occurring oil, such as vegetable oil.It should be pointed out that, although Class III base oil is derived from mineral oil, the strict processing of these fluid experiences causes their physical property to be very similar to some real synthetic oils, such as PAO.Therefore, the oil derived from Class III base oil can be called synthetic fluid in industry.The II+ class can comprise high viscosity index Class II.

[0064] The base oil blend used in the disclosed lubricating oil composition can be a mineral oil, an animal oil, a vegetable oil, a synthetic oil, a synthetic oil blend, or a mixture thereof. Suitable oils can be derived from hydrocracked, hydrogenated, hydrorefined, unrefined, refined and rerefined oils and mixtures thereof.

[0065] Unrefined oils are those derived from natural, mineral or synthetic sources with little or no further purification. Refined oils are similar to unrefined oils, except that they have been subjected to one or more purification steps, which may result in improvements in one or more properties. Examples of suitable purification techniques are solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Oils refined to edible quality may or may not be useful. Edible oils may also be referred to as white oils. In some embodiments, the lubricating oil composition does not contain edible oils or white oils.

[0066] Re-refined oils are also known as reclaimed or reprocessed oils. Similar to refined oils, these oils are obtained using the same or similar processes. Typically, these oils are further treated with techniques aimed at removing spent additives and oil breakdown products.

[0067] Mineral oil can comprise the oil obtained by drilling or the oil from plants and animals or their any mixture.For example, this type of oil can include but not limited to castor oil, lard, olive oil, peanut oil, corn oil, soybean oil and linseed oil, and mineral lubricating oil, such as liquid petroleum and solvent-treated or acid-treated paraffin, cycloparaffin or mixed paraffin-cycloparaffin type mineral lubricating oil.If desired, this type of oil can be partially or completely hydrogenated.The oil deriving from coal or shale can also be useful.

[0068] Useful synthetic lubricating oils may include hydrocarbon oils such as polymerized, oligomeric or copolymerized olefins (e.g., polybutene, polypropylene, propylene isobutylene copolymer); poly(1-hexene), poly(1-octene), 1-decene terpolymers or oligomers, such as poly(1-decene), such materials being generally referred to as α-olefins, and mixtures thereof; alkylbenzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di(2-ethylhexyl)-benzene); polyphenylenes (e.g., biphenyl, terphenyl, alkylated polyphenylenes); diphenylalkanes, alkylated diphenylalkanes, alkylated diphenyl ethers, and alkylated diphenyl sulfides, and derivatives, analogs, and homologs thereof, or mixtures thereof. Polyalphaolefins are typically hydrogenated materials.

[0069] Other synthetic lubricating oils include polyol esters, diesters, liquid esters (e.g., toluene phosphate, trioctyl phosphate, and diethyl ester of decanephosphonic acid) or polytetrahydrofuran (PTF). Synthetic oils can be produced by the Fischer-Tropsch reaction and can typically be hydroisomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, the oil can be prepared by the Fischer-Tropsch gas-to-liquid synthesis procedure and other gas-to-liquid oils.

[0070] The major amount of the base oil included in the lubricating composition may be selected from Group I, Group II, Group III, Group IV, Group V, and combinations of two or more of the foregoing, and wherein the major amount of the base oil is different from the base oil that would result from providing an additive component or a viscosity index improver in the composition. In another embodiment, the major amount of the base oil included in the lubricating composition may be selected from Group II, Group III, Group IV, Group V, and combinations of two or more of the foregoing, and wherein the major amount of the base oil is different from the base oil that would result from providing an additive component or a viscosity index improver in the composition.

[0071] The oil of lubricating viscosity may be present in an amount that is the remainder remaining after subtracting the total amount of performance additives (including viscosity index improvers and / or pour point depressants and / or other top treatment additives) from 100 wt %. For example, the oil of lubricating viscosity may be present in the finished fluid in a major amount, such as greater than about 50 wt %, greater than about 60 wt %, greater than about 70 wt %, greater than about 80 wt %, greater than about 85 wt %, or greater than about 90 wt %.

[0072] Optional additives :

[0073] The detergent-free and low-ash lubricating oil compositions herein may also contain a number of optional additives. Those optional additives are described in the following paragraphs.

[0074] Boron-containing compoundsIn light of the above discussion of boron content, the detergent-free, low-ash lubricating oil compositions herein may optionally contain one or more boron-containing compounds. Examples of boron-containing compounds include borate esters, borated fatty amines, borated epoxides, borated detergents, and borated dispersants, such as borated succinimide dispersants, as disclosed in U.S. Patent No. 5,883,057. The boron-containing compound, if present, may be used in an amount sufficient to provide up to about 8 weight percent, about 0.01 weight percent to about 7 weight percent, about 0.05 weight percent to about 5 weight percent, or about 0.1 weight percent to about 3 weight percent of the lubricating oil composition.

[0075] extreme pressure agents The detergent-free, low-ash lubricating composition herein may optionally contain one or more extreme pressure agents. Extreme pressure (EP) agents soluble in oil include sulfur-containing and chlorine-containing EP agents, chlorinated hydrocarbon EP agents, and phosphorus EP agents. Examples of such EP agents include chlorinated waxes; organic sulfides and polysulfides such as bisdibenzyl disulfide, bis(chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurized methyl oleate, sulfurized alkylphenols, sulfurized dipentenes, sulfurized terpenes, sulfurized Diels-Alder adducts; phosphosulfurized hydrocarbons such as the reaction products of phosphorus sulfide with turpentine or methyl oleate; phosphites such as dialkyl and trialkyl phosphites, for example, dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, amylphenyl phosphite; diamylphenyl phosphite, tridecyl phosphite, distearyl phosphite, and polypropylene-substituted phenyl phosphites; metal thiocarbamates such as zinc dioctyldithiocarbamate and barium heptylphenol dioate; amine salts of alkyl and dialkyl phosphoric acids, including, for example, amine salts of the reaction products of dialkyldithiophosphoric acids with propylene oxide; and mixtures thereof.

[0076] Friction modifiers The detergent-free, low-ash lubricating compositions herein may optionally contain one or more friction modifiers. Suitable friction modifiers may include both metal-containing and metal-free friction modifiers and may include, but are not limited to, imidazolines, amides, amines, succinimides, alkoxylated amines, alkoxylated etheramines, amine oxides, amidoamines, nitriles, betaines, quaternary amines, imines, amine salts, aminoguanidines, alkanolamides, phosphonates, metal-containing compounds, glycerides, sulfurized fatty compounds and olefins, sunflower oil, other naturally occurring plant or animal oils, dicarboxylic acid esters, esters or partial esters of polyols, and one or more aliphatic or aromatic carboxylic acids, among others.

[0077] Suitable friction modifiers may contain a hydrocarbyl group selected from a linear, branched or aromatic hydrocarbyl group or a mixture thereof, and may be saturated or unsaturated. The hydrocarbyl group may be composed of carbon and hydrogen or heteroatoms (such as sulfur or oxygen). The hydrocarbyl group may be in the range of about 12 to about 25 carbon atoms. In some embodiments, the friction modifier may be a long-chain fatty acid ester. In another embodiment, the long-chain fatty acid ester may be a monoester or a diester or a (tri)glyceride. The friction modifier may be a long-chain fatty amide, a long-chain fatty ester, a long-chain fatty epoxide derivative or a long-chain imidazoline.

[0078] Other suitable friction modifiers may include organic, ashless (metal-free), nitrogen-free organic friction modifiers. Such friction modifiers may include esters formed by reacting carboxylic acids and anhydrides with alkanols and typically contain a polar terminal group (e.g., a carboxyl or hydroxyl group) covalently bonded to an oleophilic hydrocarbon chain. An example of an organic ashless, nitrogen-free friction modifier is commonly known as glyceryl monooleate (GMO), which may contain monoesters, diesters, and triesters of oleic acid. Other suitable friction modifiers are described in U.S. Patent No. 6,723,685, which is incorporated herein by reference in its entirety.

[0079] Amine friction modifiers may include amines or polyamines. Such compounds may have linear chains, saturated or unsaturated hydrocarbon groups, or mixtures thereof, and may contain from about 12 to about 25 carbon atoms. Other examples of suitable friction modifiers include alkoxylated amines and alkoxylated etheramines. Such compounds may have linear chains, saturated or unsaturated hydrocarbon groups, or mixtures thereof. They may contain from about 12 to about 25 carbon atoms. Examples include ethoxylated amines and ethoxylated etheramines.

[0080] Amines and amides can be used as such or as adducts or reaction products with boron compounds such as boron oxide, boron halides, metaborates, boric acid, or mono-, di-, or tri-alkyl borate esters. Other suitable friction modifiers are described in U.S. Patent No. 6,300,291, which is incorporated herein by reference in its entirety.

[0081] Friction modifiers may optionally be present in a range such as from about 0 wt% to about 10 wt%, or from about 0.01 wt% to about 8 wt%, or from about 0.1 wt% to about 4 wt%.

[0082] Compounds containing transition metals In another embodiment, and in accordance with the above discussion regarding total metal content, the detergent-free, low-ash lubricants herein may optionally include transition metal-containing compounds or metalloids. Transition metals may include, but are not limited to, titanium, vanadium, copper, zinc, zirconium, molybdenum, tantalum, tungsten, and the like. Suitable metalloids include, but are not limited to, boron, silicon, antimony, tellurium, and the like.

[0083] In one embodiment, the oil-soluble transition metal-containing compound can function as an antiwear agent, a friction modifier, an antioxidant, a deposit control additive, or more than one of these functions. In one embodiment, the oil-soluble transition metal-containing compound can be an oil-soluble titanium compound, such as titanium (IV) alkoxide. Among the titanium-containing compounds that can be used in the disclosed technology or can be used to prepare the oil-soluble materials of the disclosed technology are various Ti (IV) compounds, such as titanium (IV) oxide; titanium (IV) sulfide; titanium (IV) nitrate; titanium (IV) alkoxides, such as titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, titanium 2-ethylhexoxide; and other titanium compounds or complexes, including but not limited to titanium phenoxides; titanium carboxylates, such as titanium (IV) 2-ethyl-1-3-adipate or titanium citrate or titanium oleate; and (triethanolamine) titanium (IV) isopropoxide. Other forms of titanium encompassed within the disclosed technology include titanium phosphates, such as titanium dithiophosphates (e.g., titanium dialkyldithiophosphates), and titanium sulfonates (e.g., titanium alkylbenzenesulfonates), or generally titanium compounds reacted with various acidic materials to form reaction products of salts (e.g., oil-soluble salts). Titanium compounds are therefore particularly derivable from organic acids, alcohols, and glycols. Ti compounds can also exist in dimerized or oligomeric forms, containing Ti--O--Ti structures. Such titanium materials are commercially available or can be readily prepared by appropriate synthesis techniques readily known to those skilled in the art. They exist at room temperature in solid or liquid form, depending on the specific compound. They can also be provided in the form of solutions in suitable inert solvents.

[0084] In one embodiment, titanium can be supplied as a Ti-modified dispersant, such as a succinimide dispersant. Such materials can be prepared by forming a titanium mixed anhydride between a titanium alkoxide and a hydrocarbyl-substituted succinic anhydride, such as an alkenyl (or alkyl) succinic anhydride. The resulting titanate-succinate intermediate can be used directly, or it can be reacted with any of a number of materials, such as (a) a polyamine-based succinimide / amide dispersant having free, condensable --NH functional groups; (b) components of a polyamine-based succinimide / amide dispersant, namely alkenyl (or alkyl) succinic anhydride and a polyamine, (c) a hydroxyl-containing polyester dispersant prepared by reacting a substituted succinic anhydride with a polyol, amino alcohol, polyamine, or mixtures thereof. Alternatively, the titanate-succinate intermediate can be reacted with other agents, such as alcohols, amino alcohols, ether alcohols, polyether alcohols, or polyols, or fatty acids, and the product used directly to impart Ti to the lubricant, or further reacted with a succinic acid dispersant as described herein. As an example, 1 part (by mole) of tetraisopropyl titanate can be reacted with about 2 parts (by mole) of polyisobutylene-substituted succinic anhydride at 140° C. to 150° C. for 5 to 6 hours to provide a titanium-modified dispersant or intermediate. The resulting material (30 g) can also be reacted with a succinimide dispersant from polyisobutylene-substituted succinic anhydride and polyethylene polyamine mixture (127 g + diluent oil) at 150° C. for 1.5 hours to produce a titanium-modified succinimide dispersant.

[0085] Another titanium-containing compound can be titanium alkoxide with C6 to C 25 The reaction product of carboxylic acid. The reaction product can be represented by the following formula:

[0086]

[0087] wherein n is an integer selected from 2, 3, and 4, and R is a hydrocarbyl group containing from about 5 to about 24 carbon atoms, or is represented by the formula:

[0088]

[0089] wherein m+n=4 and n is in the range of 1 to 3, R4 is an alkyl moiety having a carbon atom range of 1 to 8, R1 is selected from a hydrocarbyl group containing about 6 to 25 carbon atoms, and R2 and R3 are the same or different and are selected from a hydrocarbyl group containing about 1 to 6 carbon atoms, or the titanium compound may be represented by the formula:

[0090]

[0091] wherein x is in the range of 0 to 3, R1 is selected from a hydrocarbon group containing about 6 to 25 carbon atoms, R2 and R3 are the same or different and are selected from a hydrocarbon group containing about 1 to 6 carbon atoms, and R4 is selected from H, or C6 to C 25 A group consisting of carboxylic acid moieties.

[0092] Suitable carboxylic acids may include, but are not limited to, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, oleic acid, erucic acid, linoleic acid, linolenic acid, cyclohexanecarboxylic acid, phenylacetic acid, benzoic acid, neodecanoic acid, and the like.

[0093] In one embodiment, the oil-soluble titanium compound may be present in the lubricating oil composition in an amount providing 0 to 3000 ppm by weight titanium, or 25 to about 1500 ppm by weight titanium, or about 35 to 500 ppm by weight titanium, or about 50 to about 300 ppm by weight.

[0094] Viscosity index improvers The detergent-free, low-ash lubricating oil compositions herein may optionally contain one or more viscosity index improvers, such as dispersant olefin copolymer viscosity index improvers. Suitable viscosity index improvers may include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutylene, hydrogenated styrene-isoprene polymers, styrene / maleic acid ester copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, α-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkyl styrenes, hydrogenated alkenyl aryl conjugated diene copolymers, or mixtures thereof. Viscosity index improvers may include star polymers, and suitable examples are described in U.S. Publication No. 20120101017A1.

[0095] The lubricating oil compositions herein may optionally contain one or more dispersant viscosity index improvers in addition to or in place of the viscosity index improvers. Suitable viscosity index improvers may include functionalized polyolefins, for example, ethylene-propylene copolymers that have been functionalized with the reaction product of an acylating agent (such as maleic anhydride) and an amine; polymethacrylates functionalized with amines; or esterified maleic anhydride-styrene copolymers reacted with amines.

[0096] In one approach, a suitable dispersant olefin copolymer viscosity index improver comprises the reaction product of an acylated olefin copolymer and a polyamine, wherein the acylated olefin copolymer comprises an olefin copolymer having from about 0.3 to about 0.75 carboxyl groups grafted thereon per 1000 number average molecular weight units of the olefin copolymer, and wherein the olefin copolymer has a number average molecular weight of from about 40,000 to about 150,000, and wherein the polyamine is an N-arylphenylenediamine. In an optional approach, the detergent-free, low-ash lubricating composition comprises from about 1 weight percent to about 4 weight percent of the dispersant olefin copolymer viscosity index improver.

[0097] Other optional additivesOther additives may be selected to perform one or more functions required of the lubricating fluid. In addition, one or more of the additives mentioned may be multifunctional and provide functionality in addition to or different from the functionality specified herein. Other performance additives may be additives in addition to the specific additives disclosed herein and / or may include one or more of the following: metal passivators, viscosity index improvers, ashless TBN promoters, friction modifiers, antiwear agents, corrosion inhibitors, rust inhibitors, dispersants, dispersant viscosity index improvers, extreme pressure agents, antioxidants, foam inhibitors, demulsifiers, emulsifiers, pour point depressants, seal swell agents, and mixtures thereof. Typically, a fully formulated lubricating oil will contain one or more of these performance additives, subject to the above discussion of the components, amounts, and relationships of the various composition ingredients.

[0098] Suitable metal deactivators may include derivatives of benzotriazole (typically tolyltriazole), dimercaptothiadiazole derivatives, 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole or 2-alkyldithiobenzothiazole; foam inhibitors including copolymers of ethyl acrylate and 2-ethylhexyl acrylate and optionally vinyl acetate; demulsifiers including trialkyl phosphates, polyethylene glycol, polyethylene oxide, polypropylene oxide and (ethylene oxide-propylene oxide) polymers; pour point depressants including esters of maleic anhydride-styrene, polymethacrylates, polyacrylates or polyacrylamides.

[0099] Suitable suds suppressors include silicon-based compounds such as siloxanes.

[0100] Suitable pour point depressants may include polymethyl methacrylate or mixtures thereof. The pour point depressant may be present in an amount sufficient to provide from about 0 wt % to about 1 wt %, from about 0.01 wt % to about 0.5 wt %, or from about 0.02 wt % to about 0.04 wt % based on the final weight of the lubricating oil composition.

[0101] Suitable additional rust inhibitors can be single compounds or mixtures of compounds having properties that inhibit corrosion of ferrous metal surfaces. Additional rust inhibitors may be provided as long as they do not conflict with the corrosion inhibitors selected above. In addition to the above-mentioned rust inhibitors, non-limiting examples of rust inhibitors include: oil-soluble high molecular weight organic acids such as 2-ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, and cerotic acid; and oil-soluble polycarboxylic acids including dimer acids and trimer acids, such as those produced by pine oil fatty acids, oleic acid, and linoleic acid. Other suitable corrosion inhibitors include long-chain α,ω-dicarboxylic acids having a molecular weight in the range of about 600 to about 3000, and alkenyl succinic acids in which the alkenyl group contains about 10 or more carbon atoms, such as tetrapropenyl succinic acid, tetradecenyl succinic acid, and hexadecenyl succinic acid. Another useful type of acidic corrosion inhibitor is the half ester of an alkenyl succinic acid having from about 8 to about 24 carbon atoms in the alkenyl group and an alcohol such as polyethylene glycol. The corresponding half amides of such alkenyl succinic acids are also useful. Useful rust inhibitors are high molecular weight organic acids.

[0102] Rust inhibitors, if present, may be used in amounts sufficient to provide from about 0 wt % to about 5 wt %, from about 0.01 wt % to about 3 wt %, from about 0.1 wt % to about 2 wt %, based on the final weight of the lubricating oil composition.

[0103] Generally speaking, suitable detergent-free, low-ash lubricants herein can include additive components within the ranges listed in the table below.

[0104] Table 2: Suitable low ash lubricating compositions

[0105]

[0106]

[0107] The percentages (wt %) of each component above represent the weight percentage of each component, based on the weight of the final lubricating oil composition. The remainder of the lubricating oil composition consists of one or more base oils. The additives used to formulate the compositions described herein can be blended into the base oil individually or in various sub-combinations. However, it may be appropriate to use an additive concentrate (i.e., additives plus a diluent, such as a hydrocarbon solvent) to blend all components simultaneously. A fully formulated lubricant typically contains an additive package, referred to herein as a dispersant / inhibitor package or DI package, which will supply the desired characteristics in the formulation.

[0108] Lubricants herein are configured to be used in various types of lubricants, such as automotive lubricants and / or greases, internal combustion engine oils, hybrid engine oils, electric engine lubricants, transmission lubricants, transmission lubricants, gear oils, hydraulic lubricants, tractor hydraulic fluids, metal working fluids, turbine engine lubricants, stationary engine lubricants, tractor lubricants, motorcycle lubricants, power steering fluids, clutch fluids, axle fluids, wet crushing fluids, etc. Suitable engine types may include, but are not limited to, heavy-duty diesel engines, passenger cars, light-duty diesel engines, medium-speed diesel engines, or marine engines. The internal combustion engine may be a diesel fuel engine, a gasoline fuel engine, a natural gas fuel engine, a biofuel engine, a mixed diesel / biofuel fuel engine, a mixed gasoline / biofuel fuel engine, an alcohol fuel engine, a mixed gasoline / alcohol fuel engine, a compressed natural gas (CNG) fuel engine, or a mixture thereof. The diesel engine may be a compression ignition engine. The gasoline engine may be a spark ignition engine. The internal combustion engine may also be used in combination with a power source or battery power source. The engine thus constructed is generally referred to as a hybrid engine. The internal combustion engine may be a 2-stroke, 4-stroke, or rotary engine. Suitable internal combustion engines include marine diesel engines (such as inland boats), aviation piston engines, low load diesel engines and motorcycle, car, locomotive and truck engines.The engine may be coupled to a turbocharger.

[0109] The terms "oil composition," "lubricating composition," "lubricating oil composition," "lubricating oil," "lubricant composition," "fully formulated lubricant composition," "lubricant," "crankcase oil," "crankcase lubricant," "engine oil," "engine lubricant," "motor oil," and "motor lubricant" are considered to be fully interchangeable synonymous terms referring to a finished lubricating product comprising a major base oil plus a minor additive composition.

[0110] As used herein, the terms "additive package," "additive concentrate," "additive composition," "engine oil additive package," "engine oil additive concentrate," "crankcase additive package," "crankcase additive concentrate," "motor oil additive package," "motor oil concentrate" are considered to be fully interchangeable synonymous terms and refer to that portion of a lubricating oil composition that excludes the bulk base oil stock blend. The additive package may or may not include a viscosity index improver or pour point depressant.

[0111] The term "overbased" relates to metal salts, such as metal salts of sulfonates, carboxylates, salicylates and / or phenates, in which the metal is present in an amount exceeding the stoichiometric amount. Such salts may have a conversion level exceeding 100% (i.e., they may contain more than 100% of the theoretical amount of metal required to convert the acid into its "normal" salt, "neutral" salt). The expression "metal ratio" is often abbreviated to MR, which is used to express the ratio of the total chemical equivalents of the metal in the overbased salt to the chemical equivalents of the metal in the neutral salt, based on known chemical reactivity and stoichiometry. In normal or neutral salts, the metal ratio is one, while in overbased salts, MR is greater than one. They are often referred to as overbased, superbased or ultrabased salts and may be salts of organic sulfuric acids, carboxylic acids, salicylates, sulfonic acids and / or phenols.

[0112] The term "alkaline earth metals" refers to calcium, barium, magnesium and strontium, and the term "alkali metals" refers to lithium, sodium, potassium, rubidium and cesium.

[0113] As used herein, the term "hydrocarbyl" or "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from a hydrocarbon substituent and a hydrocarbon substituent substituted with one or more of a halogen group, a hydroxyl group, an alkoxy group, a mercapto group, a nitro group, a nitroso group, an amino group, a pyridyl group, a furyl group, an imidazolyl group, oxygen, and nitrogen, and wherein no more than two non-hydrocarbon substituents are present for every ten carbon atoms in the hydrocarbyl group.

[0114] As used herein, the term "alkylene substituent" or "alkylene group" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group that is directly attached to the remainder of the molecule at two positions in the molecule through carbon atoms and has predominantly hydrocarbon character. Each alkylene group is independently selected from divalent hydrocarbon substituents, and substituted divalent hydrocarbon substituents containing the following: halo groups, alkyl groups, aryl groups, alkaryl groups, aralkyl groups, hydroxyl groups, alkoxy groups, mercapto groups, nitro groups, nitroso groups, amino groups, pyridyl groups, furyl groups, imidazolyl groups, oxygen, and nitrogen, and wherein there are no more than two non-hydrocarbon substituents for every ten carbon atoms in the alkylene group.

[0115] Unless expressly stated otherwise, as used herein, the term "wt%" refers to the percentage of the component by weight of the entire composition.

[0116] As used herein, unless expressly stated otherwise, the term "ppm" or "ppmw" means parts per million on a weight basis.

[0117] As used herein, the terms "soluble," "oil-soluble," or "dispersible" may, but do not necessarily, mean that a compound or additive is soluble, dissolvable, miscible, or capable of being suspended in oil in all proportions. However, the aforementioned terms do mean that they are, for example, soluble, suspendable, dissolvable, or stably dispersible in the oil to an extent sufficient to exert their intended effect in the environment in which the oil is employed. Furthermore, the additional incorporation of other additives may also allow for the incorporation of higher levels of a particular additive, if desired.

[0118] As used herein, the term "TBN" is used to denote total base number in mg KOH / g as measured by the method of ASTM D2896.

[0119] As used herein, the term "alkyl" refers to a straight chain, branched chain, cyclic and / or substituted saturated chain moiety having from about 1 to about 100 carbon atoms. As used herein, the term "alkenyl" refers to a straight chain, branched chain, cyclic and / or substituted unsaturated chain moiety having from about 3 to about 10 carbon atoms. As used herein, the term "aryl" refers to monocyclic and polycyclic aromatic compounds, which may include alkyl, alkenyl, alkaryl, amino, hydroxyl, alkoxy, halo substituents and / or heteroatoms, including but not limited to nitrogen, oxygen, and sulfur.

[0120] As used herein, "post-reacted" or "post-treated" refers to a component that has been further reacted or treated with, for example, boron, phosphorus, and / or maleic anhydride, and may refer to a dispersant in which a primary and / or secondary amine has been further reacted with such compounds to convert at least a portion of such amine to a tertiary amine. Such subsequent reactions or treatments are further described in US Pat. No. 5,241,003, which is incorporated herein by reference. In contrast, a "non-post-reacted" or "non-post-treated" component has not undergone such further processing, reaction, and / or treatment and, in the case of a dispersant, includes an amount of a primary and / or secondary amine.

[0121] The molecular weight of any embodiment herein can be measured using a gel permeation chromatography (GPC) instrument such as a Waters instrument and the data processed using software such as the Waters Empower software. The GPC instrument can be equipped with a Waters separation module and a Waters refractive index detector (or similar optional equipment). GPC operating conditions can include a guard column, four Agilent PLgel columns (300×7.5 mm in length; a particle size of 5 μm and a pore size range of ), the column temperature is about 40 ° C. Unstabilized HPLC grade tetrahydrofuran (THF) can be used as a solvent, and the flow rate is 1.0 mL / min. The GPC instrument can be calibrated with commercially available polystyrene (PS) standards with a narrow molecular weight distribution ranging from 500 g / mol to 380,000 g / mol. For samples with a mass of less than 500 g / mol, the calibration curve can be extrapolated. The sample and PS standard can be dissolved in THF and prepared at a concentration of 0.1 wt % to 0.5 wt % and used without filtering. GPC measurements are also described in US 5,266,223, which is incorporated herein by reference. The GPC method also provides molecular weight distribution information; see, for example, W.W. Yau, J.J. Kirkland and D.B. Ly, "Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New York, 1979, which is incorporated herein by reference.

[0122] As used herein, "sulfated ash" or "SASH" refers to the amount of sulfated ash measured using ASTM D874. Alternatively, sulfated ash can also be calculated based on the amount of metals in the lubricant. For example, sulfated ash (SASH) can optionally be calculated based on the total metal elements that contribute to the SASH in the lubricant composition, adjusted by a factor for each metal type. Metals that contribute to SASH include (along with the adjustment factors) barium (1.7), boron (3.22), calcium (3.4), copper (1.252), lead (1.464), lithium (7.92), magnesium (4.95), manganese (1.291), molybdenum (1.5), potassium (2.33), sodium (3.09), and zinc (1.5). Specifically, the ppmw content of each of the metal elements present in the lubricating oil composition that are believed to contribute to sulfated ash is multiplied by its corresponding factor as described above; the products of each metal element / factor adjustment are then added together and the sum is divided by 10,000 to calculate the weight percent of SASH in the lubricating composition. Unless otherwise noted, all sulfated ash levels herein are measured using ASTM D874.

[0123] Example

[0124] The present disclosure and its many advantages may be better understood by the following examples. The following examples are illustrative and do not limit the scope or spirit thereof. Those skilled in the art will readily appreciate that variations of the components, methods, steps, and apparatus described in these examples may be used. Unless otherwise indicated or apparent from the context of the following examples and the discussion throughout this disclosure, all percentages, ratios, and parts mentioned in this disclosure are by weight.

[0125] To demonstrate how a detergent-free, low-ash lubricant as defined herein can achieve suitable performance as a passenger car motor oil when element relationships are selected rather than incorporating new additives, the passenger car motor oils of the present invention and comparative passenger car motor oils were evaluated for high-temperature deposits (TEOST-33) as measured according to ASTM D6335, total weighted piston deposits (WPD) according to the "Sequence IIIH Test" of ASTM D8111, and average engine sludge (AES) and average engine varnish (AEV) according to the "Sequence VH Test" of ASTM D8256. The passenger car motor oils of this example all included similar amounts of defoaming additives, process oils, pour point dispersants, viscosity improvers, and Group III base oils to form lubricants with kV100 viscosities (ASTM D445) ranging from about 10 cSt to about 12 cSt. The comparative lubricants and the inventive lubricants also included the following additives from Table 1 and, when included, had the fluid relationships shown in Table 2 below:

[0126] · Dispersant Disp-1 : A succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 1000 to about 2000 and post-treated with a boron compound.

[0127] · Dispersant Disp-2 : A succinimide dispersant derived from polyisobutylene having a number average molecular weight greater than about 2000.

[0128] · Dispersant Disp-3 : A succinimide dispersant derived from polyisobutylene having a number average molecular weight of 1000 to about 2000.

[0129] · Detergent 1 (Det-1) : Overbased calcium sulfonate with a TBN of about 300.

[0130] · Detergent 2 (Det-2) : Overbased magnesium sulfonate with a TBN of about 400.

[0131] · Antiwear Agent 1 (AW1) : 3-[[Bis(2-methylpropoxy)phosphinothio]thio]-2-methylpropanoic acid.

[0132] · Antiwear Agent 2 (AW 2) : Zinc dialkyldithiophosphate having alkyl groups derived 100% from primary alcohols.

[0133] · Antiwear Agent 3 (AW 3) : Zinc dialkyldithiophosphate having alkyl groups derived 100% from secondary alcohols.

[0134] · Antioxidant 1 (AO 1) : Dialkyldiphenylamine antioxidant.

[0135] · Antioxidant 2 (AO 2): Phenolic ester antioxidant.

[0136] · Antioxidant 3 (AO3) : Molybdenum-containing antioxidant.

[0137] · Antioxidant 4 (AO 4) : Sulfur-containing antioxidant.

[0138] · Viscosity regulator (DOCP1) : A dispersant olefin copolymer viscosity modifier grafted with N-arylphenylenediamine having a number average molecular weight of 40,000 to 150,000.

[0139] Table 1: Fluid composition

[0140]

[0141]

[0142] Table 2: Fluid relationships

[0143] Present invention 1 Comparative composition 1 Comparative composition 2 KV100℃(D445) cSt 10.9 9.8 10.6 B ppm 87 58 237 Ca ppm 1 1246 1296 Mg ppm 4 368 559 Mo ppm 0 51 80 P ppm 359 626 737 Zn ppm 0 693 812 nitrogen ppm 1340 730 978 S ppm 536 1845 2710 TBN(D2896) mg KOH / g 4.2 6.9 8 Total dispersant weight% 5.6 2.7 4.5 Total detergent weight% 0 1.4 1.7 Nitrogen: TBN 319 106 122 S:P 1.49 2.95 3.68 (N+S+P) / B 25.7 55.2 18.7 AO vs. AW 6.5x 1.1x 1.3x Nitrogen from AO ppm 700 350 280 Nitrogen % from AO 52.2％ 47.8％ 28.6％

[0144] Table 3: Piston cleanliness

[0145] Present invention 1 Comparative composition 1 Comparative composition 2 Sulfated ash (D874) ％ 0.06 0.72 0.84 Sediment (D6335) Mg 28.1 21.3 24.7 WPD(D8111) advantage 4.45 4.22 4.16 AES (D8256) advantage 9.33 7.71 8.41 AEV(D8256) advantage 9.77 9.09 9.27

[0146] It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless expressly and affirmatively limited to one referent. Thus, for example, reference to "an antioxidant" includes two or more different antioxidants. As used herein, the term "comprising" and its grammatical variations are intended to be non-limiting, such that recitation of items in a list does not exclude other like items that can be substituted or added to the listed items.

[0147] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers and other numerical values expressing quantities, percentages, or ratios used in the specification and claims should be understood as being modified in all instances by the term "about." Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values that may vary depending on the desired properties sought to be obtained by the present disclosure. At a minimum, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0148] It should be understood that each component, compound, substituent or parameter disclosed herein should be interpreted as disclosed for use alone or in combination with one or more of each other component, compound, substituent or parameter disclosed herein.

[0149] It should be further understood that each range disclosed herein is to be interpreted as a disclosure of each specific value within the disclosed range with the same number of significant figures. Thus, for example, a range of 1 to 4 is to be interpreted as an explicit disclosure of the values 1, 2, 3, and 4, as well as any range of such values.

[0150] It should be understood that each lower limit of each range disclosed herein should be interpreted as disclosed in combination with each upper limit of each range disclosed herein for the same component, compound, substituent or parameter and each specific value in each range. Therefore, the disclosure should be interpreted as the disclosure of all ranges derived by combining each lower limit of each range with each upper limit of each range or with each specific value in each range, or by combining each upper limit of each range with each specific value in each range. That is, it should also be understood that any range between the endpoint values in a wide range is also discussed herein. Therefore, a range of 1 to 4 also means a range of 1 to 3, 1 to 2, 2 to 4, 2 to 3, etc.

[0151] In addition, a particular amount / value of a component, compound, substituent or parameter disclosed in this specification or the examples should be interpreted as a disclosure of the lower or upper limit of a range, and thus can be combined with any other lower or upper limit or particular amount / value of a range for the same component, compound, substituent or parameter disclosed elsewhere in this disclosure to form a range for that component, compound, substituent or parameter.

[0152] While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not presently foreseen or may not presently be foreseen may occur to the applicant or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to encompass all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims

1. A detergent-free and low-ash lubricating composition, comprising: one or more base oils of lubricating viscosity; Total sulfated ash (SASH), less than about 0.2 wt. % as measured by ASTM D874; one or more succinimide dispersants derived from polyisobutylene having a number average molecular weight of at least about 1000, wherein each of the succinimide dispersants has up to about 2 weight percent nitrogen, and wherein at least one of the succinimide dispersants is post-treated with a boron compound; one or more ashless antiwear additives; one or more antioxidants; a total base number (TBN) of at least about 4 according to ASTM D2896; at least about 1000 ppm nitrogen, no more than 100 ppm boron, no more than 800 ppm sulfur, and a sulfur-to-phosphorus ratio of 2.0 or less, and a nitrogen-to-TBN ratio of about 150 or greater; and The detergent-free, low-ash lubricating composition is substantially free of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium.

2. The detergent-free, low-ash lubricating composition of claim 1 , further comprising less than about 10 ppm of each of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium.

3. The detergent-free, low-ash lubricating composition of claim 2, further comprising no more than about 500 ppm phosphorus and no more than about 600 ppm sulfur.

4. The detergent-free and low ash lubricating composition of claim 3, wherein the composition comprises at least about 6 times the one or more antioxidants relative to the one or more ashless antiwear additives.

5. The detergent-free, low-ash lubricating composition of claim 4, wherein the total sulfated ash (SASH) measured according to ASTM D874 is less than about 0.1 wt%.

6. The detergent-free, low-ash lubricating composition of claim 1, wherein the one or more ashless antiwear additives comprise one or more ashless dialkyl dithiophosphate antiwear additives.

7. The detergent-free, low-ash lubricating composition of claim 6, wherein the one or more ashless dialkyl dithiophosphate antiwear additives have the structure of Formula I or a salt thereof: wherein R4 and R5 are independently C3 to C8 linear or branched alkyl groups, and R6 is -H or -CH3.

8. The detergent-free, low-ash lubricating composition of claim 1, wherein the one or more antioxidants comprise an aminic antioxidant, a hindered phenolic antioxidant, or a combination thereof.

9. The detergent-free and low-ash lubricating composition of claim 8, wherein the aminic antioxidant is selected from the group consisting of aromatic amines, alkylated diphenylamines, alkyldiphenylamines, dialkyldiphenylamines, octyldiphenylamine, dioctyldiphenylamine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, hindered non-aromatic amines, or combinations thereof.

10. The detergent-free, low-ash lubricating composition of claim 1 , wherein the one or more succinimide dispersants comprise: (i) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 1000 to about 2000 and post-treated with a boron compound; (ii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight greater than about 2000; and (iii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of 1000 to about 2000.

11. The detergent-free, low-ash lubricating composition of claim 1 , wherein greater than 50 weight percent of the total nitrogen is provided by the one or more antioxidants.

12. The detergent-free, low-ash lubricating composition of claim 1 , further comprising a dispersant olefin copolymer viscosity index improver comprising a reaction product of an acylated olefin copolymer and a polyamine, wherein the acylated olefin copolymer comprises an olefin copolymer having grafted thereon from about 0.3 to about 0.75 carboxyl groups per 1000 number average molecular weight units of the olefin copolymer, wherein the olefin copolymer has a number average molecular weight of from about 40,000 to about 150,000, and wherein the polyamine is an N-arylphenylenediamine.

13. The detergent-free, low-ash lubricating composition of claim 12, wherein the lubricating composition comprises from about 1 wt% to about 4 wt% of the dispersant olefin copolymer viscosity index improver.

14. The detergent-free and low-ash lubricating composition of claim 1, wherein the total amount of the nitrogen, the sulfur, and the phosphorus relative to the amount of boron (N+S+P) / B is from about 20 to about 50.

15. The detergent-free, low-ash lubricating composition of claim 1 , wherein the lubricating composition cleans piston deposits according to the "Sequence IIIH Engine Test" (ASTM D8111) with a merit rating of at least about 4 total weighted piston deposits, and wherein the lubricating composition exhibits an average engine varnish (AES) of at least 8 merit and / or an average engine sludge rating of at least 7.6 merit according to the "Sequence VH Test" (ASTM D8256).

16. A method of lubricating a combustion engine using a detergent-free, low-ash lubricating composition, the method comprising: Lubricating a combustion engine using a detergent-free, low-ash lubricating composition; wherein the detergent-free, low-ash lubricating composition comprises one or more base oils of lubricating viscosity; a total sulfated ash (SASH) of less than about 0.2 wt. % as measured by ASTM D874; one or more succinimide dispersants derived from polyisobutylene having a number average molecular weight of at least about 1000, wherein each of the succinimide dispersants has up to about 2 wt. % nitrogen, and wherein at least one of the succinimide dispersants is post-treated with a boron compound; one or more ashless antiwear additives; one or more antioxidants; a total base number (TBN) of at least about 4 according to ASTM D2896; at least about 1000 ppm nitrogen, no more than 100 ppm boron, no more than 800 ppm sulfur, and a sulfur-to-phosphorus ratio of 2.0 or less, and a nitrogen-to-TBN ratio of about 150 or greater; and wherein the detergent-free, low-ash lubricating composition is substantially free of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium; and wherein the lubricating composition cleans piston deposits according to the "Sequence IIIH Engine Test" (ASTM D8111) with a merit rating of at least about 4 total weighted piston deposits, and wherein the lubricating composition exhibits an average engine varnish (AES) of at least 8 merits and / or an average engine sludge rating of at least 7.6 merits according to the "Sequence VH Test" (ASTM D8256).

17. The method of claim 16, further comprising less than about 10 ppm each of calcium, barium, copper, lead, lithium, magnesium, sodium, molybdenum, zinc, and potassium.

18. The method of claim 17, further comprising no more than about 500 ppm phosphorus and no more than about 600 ppm sulfur.

19. The method of claim 19, wherein the composition comprises at least about 6 times the one or more antioxidants relative to the one or more ashless antiwear additives.

20. The method of claim 19, wherein the total sulfated ash (SASH) measured according to ASTM D874 is less than about 0.1 wt%.

21. The method of claim 16, wherein the one or more ashless antiwear additives comprise one or more ashless dialkyl dithiophosphate antiwear additives.

22. The method of claim 21, wherein the one or more ashless dialkyl dithiophosphate antiwear additives have the structure of Formula I or a salt thereof: wherein R4 and R5 are independently C3 to C8 linear or branched alkyl groups, and R6 is -H or -CH3.

23. The method of claim 16, wherein the one or more antioxidants comprise an aminic antioxidant, a hindered phenolic antioxidant, or a combination thereof.

24. The method of claim 23, wherein the aminic antioxidant is selected from the group consisting of aromatic amines, alkylated diphenylamines, alkyldiphenylamines, dialkyldiphenylamines, octyldiphenylamine, dioctyldiphenylamine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, hindered non-aromatic amines, or combinations thereof.

25. The method of claim 16, wherein the one or more succinimide dispersants comprise: (i) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 1000 to about 2000 and post-treated with a boron compound; (ii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight greater than about 2000; and (iii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of 1000 to about 2000.

26. The method of claim 16, wherein greater than 50 weight percent of the total nitrogen is provided by the one or more antioxidants.

27. The method of claim 16 further comprising a dispersant olefin copolymer viscosity index improver comprising the reaction product of an acylated olefin copolymer and a polyamine, wherein the acylated olefin copolymer comprises an olefin copolymer having grafted thereon from about 0.3 to about 0.75 carboxyl groups per 1000 number average molecular weight units of the olefin copolymer, wherein the olefin copolymer has a number average molecular weight of from about 40,000 to about 150,000, and wherein the polyamine is an N-arylphenylenediamine.

28. The method of claim 16, wherein the lubricating composition comprises from about 1 wt% to about 4 wt% of the dispersant olefin copolymer viscosity index improver.

29. The method of claim 16, wherein the total amount of the nitrogen, the sulfur, and the phosphorus relative to the amount of boron (N+S+P) / B is from about 20 to about 50.

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