Highly efficient engine oil composition

Abstract

The present application relates to a lubricating oil composition for internal combustion engines that advantageously exhibits improved fuel economy. The composition may comprise a major amount of an oil of lubricating viscosity, an alkaline earth metal sulfonate detergent, and a comb polymethacrylate viscosity modifier. The composition may be of SAE viscosity grade 0W-8, 0W-12, 0W-16, or 0W-20, and may be particularly useful for hybrid vehicles.

Description

[Technical field]

[0001] The present disclosure relates to lubricating oil compositions for internal combustion engines, which provide improved fuel economy. [Background technology]

[0002] Many different lubricating compositions have been attempted in the prior art. Unfortunately, prior art lubricating oils often contain friction modifiers that have been found to sometimes cause adverse effects in vehicle engines. Such adverse effects may include, for example, increased deposit formation, increased seal failure, and / or reduced seal life. Also, when friction modifiers are present in oils, for example, with certain anti-wear additives, the friction modifiers may at least partially outcompete the anti-wear additives in competing for limited surface sites. This may result in increased wear of engine parts because anti-wear films are not formed on at least some surfaces that require wear protection.

[0003] New cost-effective and efficient lubricating oil compositions that improve fuel economy are needed. It would be desirable if such lubricating oil compositions did not require the use of friction modifiers, which can adversely affect performance.

[0004] Advantageously, the present application relates to a low viscosity lubricating oil composition that may significantly improve fuel economy and does not include significant amounts of added friction modifiers. In one embodiment, the present application relates to a lubricating oil composition for an internal combustion engine that exhibits improved fuel economy, the lubricating oil composition comprising a major amount of oil of lubricating viscosity, an alkaline earth metal sulfonate detergent providing the lubricating oil composition with 1200-2200 ppm metal, and a comb polymethacrylate viscosity modifier having a PSSI of less than 15. The lubricating oil composition may be of SAE viscosity grade 0W-8, 0W-12, 0W-16, or 0W-20, may be substantially free of friction modifiers, and may have a viscosity index of greater than 200.

[0005] In another embodiment, the present application relates to a method for improving fuel economy in an internal combustion engine, the method comprising lubricating the engine with the lubricating oil composition described above, and, if desired, operating the engine for improved fuel economy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] definition The following terms are used throughout the specification and have the following meanings unless otherwise indicated.

[0007] The term "major amount" of oil of lubricating viscosity refers to an amount of base oil that is at least 40 wt% of the lubricating oil composition. In some embodiments, a "major amount" refers to an amount of base oil that is greater than 50 wt%, greater than 60 wt%, greater than 70 wt%, greater than 80 wt%, or greater than 90 wt% of the lubricating oil composition.

[0008] In the following description, all numerical values ​​disclosed herein are approximate, regardless of whether the word "about" or "approximately" is used in conjunction therewith. They may vary by 1 percent, 2 percent, 5 percent, or sometimes by 10-20 percent.

[0009] The term "internal combustion engine" refers to any engine in which the combustion of a fuel takes place with an oxidizer in a combustion chamber that is a component of the flow circuit of a working fluid. Internal combustion engines are used in hybrid vehicles and often operate at lower temperatures than internal combustion engines in conventional vehicles.

[0010] "HOB" refers to high overbased, having a TBN greater than 250 based on actives, and "LOB" refers to low overbased, having a TBN less than 100 based on actives.

[0011] The term "Total Base Number" or "TBN" refers to the level of alkalinity in an oil sample that indicates the ability of the composition to continue to neutralize corrosive acids according to ASTM Standard No. D2896 or an equivalent procedure. The test measures the change in electrical conductivity and the results are expressed as mgKOH / g (milligram equivalents of KOH required to neutralize one gram of product). Thus, a high TBN reflects a more overbased product and, as a result, a higher reserve of base to neutralize acids.

[0012] Friction modifiers commonly used in engine oil applications can be divided into two categories: organic friction modifiers such as glycerol monooleate and inorganic friction modifiers such as molybdenum dithiocarbamate. There are many different types of organic or inorganic friction modifiers. Typically, organic friction modifiers are used in the range of 0.1-1 wt. %, while inorganic modifiers range in metal concentration from 100-1000 ppm. The term "substantially free," when used in connection with "substantially free" friction modifiers, means metal concentrations of less than 0.1 wt. %, or less than 100 ppm, for organic friction modifiers.

[0013] lubricating viscosity oil The lubricating oil composition disclosed herein generally comprises at least one oil of lubricating viscosity. Any base oil known to those skilled in the art can be used as the oil of lubricating viscosity disclosed herein. Some base oils suitable for preparing lubricating oil compositions are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London, Springer, Chapters 1 and 2 (1996), and A. Sequeria, Jr., "Lubricant Base Oil and Wax Processing," New York, Marcel Decker, Chapter 6, (1994), and DV Brock, Lubrication Engineering, Vol. 43, pages 184-5, (1987), all of which are incorporated herein by reference.

[0014] Generally, the amount of base oil in a lubricating oil composition will be a "major amount" of oil of lubricating viscosity as defined above.

[0015] In certain embodiments, the base oil is or includes any natural or synthetic lubricating base oil fraction. Some non-limiting examples of synthetic oils include oils such as polyalphaolefins or PAOs, which are prepared from the polymerization of at least one alpha-olefin, such as ethylene, or from a hydrocarbon synthesis procedure using carbon monoxide and hydrogen gas, such as the Fischer-Tropsch process.

[0016] In some embodiments, the base oil has a kinematic viscosity of from about 2.5 centistokes (cSt) to about 20 cSt, from about 4 centistokes (cSt) to about 20 cSt, or from about 5 cSt to about 16 cSt at 100° C. The kinematic viscosity of the base oil or lubricant compositions disclosed herein may be measured according to ASTM D445, which is incorporated herein by reference.

[0017] In other embodiments, the base oil is or comprises a base stock or a blend of base stocks. In further embodiments, the base stocks are produced using a variety of different processes including, but not limited to, distillation, solvent refining, hydrotreating, oligomerization, esterification, and rerefining. In some embodiments, the base stock comprises a rerefined stock. In further embodiments, the rerefined stock shall be substantially free of materials introduced through manufacturing, contamination, or previous use.

[0018] In some embodiments, the base oil comprises one or more of the base stocks in one or more of Groups I-V as specified in American Petroleum Institute (API) Publication 1509, Fourteen Edition, December 1996 (i.e., API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils), which is incorporated herein by reference. The API guidelines define base stocks as lubricant components that can be produced using a variety of different processes. Groups I, II, and III base stocks are mineral oils, each with a specific range of saturates, sulfur content, and viscosity index. Group IV base stocks are polyalphaolefins (PAOs). Group V base stocks include all other base stocks not included in Groups I, II, III, or IV.

[0019] In some embodiments, the base oil comprises one or more base stocks in Group I, II, III, IV, V, or combinations thereof. In other embodiments, the base oil comprises one or more base stocks in Group II, III, IV, or combinations thereof. In further embodiments, the base oil comprises one or more base stocks in Group II, III, IV, or combinations thereof, where the base oil has a kinematic viscosity at 100° C. of from about 2.5 centistokes (cSt) to about 20 cSt, from about 4 cSt to about 20 cSt, or from about 5 cSt to about 16 cSt.

[0020] The base oil may be selected from the group consisting of natural oils of lubricating viscosity, synthetic oils of lubricating viscosity, and mixtures thereof. In some embodiments, the base oil includes base stocks obtained by isomerization of synthetic wax and slack wax, and hydrocracked base stocks produced by hydrocracking (rather than solvent extraction) aromatic and polar components of crude materials. In other embodiments, the base oil of lubricating viscosity includes natural oils, such as animal oils, vegetable oils, mineral oils (e.g., liquid petroleum oils, and solvent- or acid-treated mineral oils of the paraffinic, naphthenic, or mixed paraffinic-naphthenic types), oils derived from coal or shale, and combinations thereof. Some non-limiting examples of animal oils include bone oil, lanolin, fish oil, lard oil, dolphin oil, seal oil, shark oil, tallow oil, and whale oil. Some non-limiting examples of vegetable oils include castor oil, olive oil, peanut oil, rapeseed oil, corn oil, sesame oil, cottonseed oil, soybean oil, sunflower oil, safflower oil, hemp oil, linseed oil, tung oil, oiticica oil, jojoba oil, and meadowfoam oil. Such oils may be partially or fully hydrogenated.

[0021] In some embodiments, synthetic oils of lubricating viscosity include hydrocarbon oils and halo-substituted hydrocarbon oils, such as polymerized and interpolymerized olefins, alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl sulfides, and derivatives thereof, analogs thereof and congeners thereof. In other embodiments, synthetic oils include alkylene oxide polymers, interpolymers, copolymers, and derivatives thereof in which the terminal hydroxyl groups may be modified by esterification, etherification, and the like. In further embodiments, synthetic oils include esters of dicarboxylic acids with various alcohols. In certain embodiments, synthetic oils include C5-C 12 Included are esters made from monocarboxylic acids and polyols and polyol ethers. In a further embodiment, the synthetic oils include tri-alkyl phosphate ester oils, such as tri-n-butyl phosphate and tri-iso-butyl phosphate.

[0022] In some embodiments, the synthetic oils of lubricating viscosity include silicon-based oils (such as polyakyl-, polyaryl-, polyalkoxy-, polyaryloxy-siloxane oils and silicate oils), hi other embodiments, the synthetic oils include liquid esters of phosphorus-containing acids, polymeric tetrahydrofurans, polyalphaolefins, and the like.

[0023] Base oils derived from the hydroisomerization of wax may also be used, either alone or in combination with the aforementioned natural and / or synthetic base oils. Such wax isomerate oils are produced by the hydroisomerization of natural or synthetic waxes or mixtures thereof over a hydroisomerization catalyst.

[0024] In further embodiments, the base oil comprises a poly-alpha-olefin (PAO). Generally, the poly-alpha-olefins can be derived from alpha-olefins having from about 2 to about 30, from about 4 to about 20, or from about 6 to about 16 carbon atoms. Non-limiting examples of suitable poly-alpha-olefins include those derived from octene, decene, mixtures thereof, and the like. These poly-alpha-olefins can have a viscosity of from about 2 to about 15, from about 3 to about 12, or from about 4 to about 8 centistokes at 100° C. In some examples, the poly-alpha-olefins can be used together with other base oils, such as mineral oils.

[0025] In further embodiments, the base oil comprises a polyalkylene glycol or a polyalkylene glycol derivative in which the terminal hydroxyl group of the polyalkylene glycol may be modified by esterification, etherification, acetylation, etc. Non-limiting examples of suitable polyalkylene glycols include polyethylene glycol, polypropylene glycol, polyisopropylene glycol, and combinations thereof. Non-limiting examples of suitable polyalkylene glycol derivatives include ethers of polyalkylene glycols (e.g., methyl ether of polyisopropylene glycol, diphenyl ether of polyethylene glycol, diethyl ether of polypropylene glycol, etc.), mono- and polycarboxylic acid esters of polyalkylene glycols, and combinations thereof. In some examples, the polyalkylene glycol or polyalkylene glycol derivative may be used together with other base oils, such as poly-alpha-olefins and mineral oils.

[0026] In further embodiments, the base oil comprises any of the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc.) with various alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc.). Non-limiting examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, 2-ethylhexyl diester of linoleic acid dimer, etc.

[0027] In a further embodiment, the base oil comprises hydrocarbons prepared by the Fischer-Tropsch process, which uses a Fischer-Tropsch catalyst to prepare hydrocarbons from gases containing hydrogen and carbon monoxide. These hydrocarbons may require further processing to be useful as base oils. For example, the hydrocarbons may be dewaxed, hydroisomerized, and / or hydrocracked using processes known to those skilled in the art.

[0028] In further embodiments, the base oil comprises unrefined oil, refined oil, re-refined oil, or mixtures thereof. Unrefined oils are those obtained directly from natural or synthetic sources without further purification treatment. Non-limiting examples of unrefined oils include shale oil obtained directly from retorting procedures, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from esterification processes, which are used without further treatment. Refined oils are similar to unrefined oils, but the former have been further treated by one or more purification processes to improve one or more properties. Many such purification processes are known to those skilled in the art, such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Re-refined oils are obtained by applying processes similar to those used to obtain refined oils to refined oils. Such re-refined oils are also known as reclaimed or reprocessed oils, and are often additionally treated by processes related to the removal of spent additives and oil breakdown products.

[0029] Alkaline Earth Metal Sulfonate Detergents The lubricating oil composition typically includes an alkaline earth metal sulfonate detergent. The alkaline earth metal sulfonate detergent is not particularly limited, but some embodiments include a magnesium sulfonate detergent, a calcium sulfonate detergent, or a mixture thereof. In some embodiments, the sulfonate detergent may be at least partially replaced or supplemented with a phenate-based detergent.

[0030] The amount and type of alkaline earth metal sulfonate and / or phenate detergent can vary, but is typically selected to provide the lubricating oil composition with at least about 1200 ppm, or at least about 1300 ppm, or at least about 1400 ppm of metal, whereas the amount and type of alkaline earth metal sulfonate detergent is usually selected to provide the lubricating oil composition with less than about 2200 ppm, or less than about 2100 ppm, or less than about 2000 ppm of metal.

[0031] The lubricating oil composition may contain a second detergent in addition to the alkaline earth metal detergent described above, as long as the second detergent does not adversely affect the improved fuel efficiency of the composition.Some non-limiting examples of suitable metal detergents include sulfurized or non-sulfurized alkyl or alkenyl phenates, alkyl or alkenyl aromatic sulfonates, boronated sulfonates, sulfurized or non-sulfurized metal salts of multi-hydroxy alkyl or alkenyl aromatic compounds, alkyl or alkenyl hydroxy aromatic sulfonates, sulfurized or non-sulfurized alkyl or alkenyl naphthenates, metal salts of alkanoic acids, metal salts of alkyl or alkenyl multiacids, and chemical and physical mixtures thereof.Other non-limiting examples of suitable metal detergents include metal sulfonates, phenates, salicylates, phosphonates, thiophosphonates, and combinations thereof.The metal may be any metal suitable for making sulfonate, phenate, salicylate, or phosphonate detergents. Non-limiting examples of suitable metals include alkali metals, alkaline metals, and transition metals, hi some embodiments, the metals are Ca, Mg, Ba, K, Na, Li, and the like.

[0032] Some suitable detergents are described in Mortier et al., “Chemistry and Technology of Lubricants,” 2nd Edition, London, Springer, Chapter 3, pages 75-85 (1996), and Leslie R. Rudnick, “Lubricant Additives: Chemistry and Applications,” New York, Marcel Dekker, Chapter 4, pages 113-136 (2003), both of which are incorporated herein by reference.

[0033] The detergent may include at least one highly overbased (greater than 250 TBN on an actives basis) sulfonate detergent, such as highly overbased calcium sulfonate, and at least one non-sulfonate detergent, such as a phenate detergent.

[0034] Additional detergents that may be used include oil-soluble overbased sulfonates, non-sulfonate containing phenates, sulfurized phenates, salixarates, salicylates, saligenins, complex detergents and naphthenate detergents, as well as other oil-soluble alkyl hydroxybenzoates of metals, particularly alkali or alkaline earth metals such as barium, sodium, potassium, lithium, calcium, and magnesium. The most commonly used metals are calcium and magnesium (both of which may be present in detergents used in lubricants), as well as mixtures of calcium and / or magnesium with sodium.

[0035] Overbased metal detergents are generally produced by carbonating a mixture of a hydrocarbon, a detergent acid such as a sulfonic acid, an alkyl hydroxybenzoate, a metal oxide or hydroxide (e.g., calcium oxide or hydroxide), and promoters such as xylene, methanol, and water. For example, to prepare an overbased calcium sulfonate, in carbonation, calcium oxide or hydroxide is reacted with carbon dioxide gas to form calcium carbonate. The sulfonic acid is neutralized with an excess of CaO or Ca(OH)2 to form a sulfonate.

[0036] The overbased detergent can be an overbased salt with low overbasing, e.g., a TBN of less than 100 based on the active content. In one embodiment, the TBN of the low overbased salt can be about 10, about 20, or about 30 to about 100. In another embodiment, the TBN of the low overbased salt can be about 30 to about 80. The overbased detergent can be an overbased salt with medium overbasing, e.g., a TBN of about 100 to about 250 based on the active content. In one embodiment, the TBN of the medium overbased salt can be about 100 to about 200. In another embodiment, the TBN of the medium overbased salt can be about 125 to about 175. The overbased detergent can be an overbased salt with high overbasing, e.g., a TBN of more than 250 based on the active content. In one embodiment, the TBN of the high overbased salt can be about 250 to about 800 based on the active content.

[0037] In one embodiment, the detergent may be one or more alkali or alkaline earth metal salts of alkyl-substituted hydroxyaromatic carboxylic acids. Suitable hydroxyaromatic compounds include mononuclear monohydroxy and polyhydroxy aromatic hydrocarbons having 1 to 4, preferably 1 to 3, hydroxyl groups. Suitable hydroxyaromatic compounds include phenol, catechol, resorcinol, hydroquinone, pyrogallol, cresol, and the like.

[0038] Non-dispersed comb polymethacrylate Non-dispersed comb polymethacrylate (comb PMA) is a comb polymer that can be used as a viscosity modifier or viscosity index improver. In one embodiment, the comb PMA used herein has a permanent shear stability index (PSSI) according to ASTM D7109 (Kurt Orbahn shear stability) of less than 15, or less than 10, or less than 5, or less than 1.

[0039] In one embodiment, the non-dispersed comb PMA has a weight average molecular weight (Mw) of 300,000 g / mol to 600,000 g / mol, 350,000 g / mol to 550,000 g / mol, 375,000 g / mol to 500,000 g / mol, or 390,000 g / mol to 460,000 g / mol.

[0040] In one embodiment, the non-dispersed comb PMA has a number average molecular weight (Mn) of 35,000 g / mol to 105,000 g / mol, 45,000 g / mol to 95,000 g / mol, 55,000 g / mol to 85,000 g / mol, or 65,000 g / mol to 75,000 g / mol. In another embodiment, the non-dispersed comb PMA has a number average molecular weight (Mn) of 150,000 g / mol to 250,000 g / mol or 200,000 g / mol to 215,000 g / mol.

[0041] In one embodiment, the non-dispersed comb PMA has a shear stability index (SSI) of 0.1 to 1.0, 0.2 to 0.9, or 0.3 to 0.8.

[0042] The non-dispersant comb PMA of the lubricating oil composition may be described as described in US2017 / 0298287A1 and JP2019014802, the disclosures of which are incorporated herein by reference. The non-dispersant comb PMA may be provided by Viscoplex® viscosity index improvers 3-201 and / or 3-162, available from Evonik.

[0043] According to one embodiment, the non-dispersed comb PMA is provided by a compound called Viscoplex® 3-201, which contains comb PMA as the resin base. The non-dispersed comb PMA has a weight average molecular weight (Mw) of 420,000 g / mol, a number average molecular weight (Mn) of 70,946 g / mol, and a Mw / Mn of 5.92. The compound has at least a unit derived from a macromonomer having a Mn of 500 or more. The non-dispersed comb PMA is present in an amount of 19% by weight based on the total weight of the compound.

[0044] According to another embodiment, the non-dispersed comb PMA is provided by a compound designated Viscoplex® 3-162, which also includes comb PMA as the resin base, and has a weight average molecular weight (Mw) of 399,292 g / mol, a number average molecular weight (Mn) of 205,952 g / mol, an Mw / Mn of 1.94, and a permanent shear stability index (PSSI) of 0.6, as measured by ASTM D7109.

[0045] According to another embodiment, the non-dispersed comb PMA is provided by a combination of compounds, for example, a combination of Viscoplex® 3-201 and Viscoplex® 3-162.

[0046] The non-dispersed comb PMA is typically present in an amount of 0.5% to 25%, 1% to 20%, 2% to 18%, 4% to 16%, or 5% to 15% by weight based on the total weight of the lubricating oil composition.

[0047] Non-dispersant comb PMA viscosity modifiers have been unexpectedly discovered to provide enhanced performance compared to other viscosity modifiers such as linear poly(meth)acrylate (PMA), olefin copolymer (OCP), and hydrogenated star diene (HSD) type viscosity index improvers. Linear poly(meth)acrylate viscosity modifiers are generally synthesized by simple free radical copolymerization of a mixture of different alkyl methacrylates. Unlike comb PMAs, conventional linear PMAs are characterized by the presence of primarily short chain length alkyls (typically 1-50 carbons) and the lack of long chain alkyl macromonomers that give comb polymers their characteristic shape. See U.S. Pat. Nos. 3,607,749 and 8,778,857, and European Patent 0225,598. Olefin copolymer viscosity modifiers typically contain ethylene and propylene and may, in some cases, contain a diene as a third monomer. See, for example, U.S. Patents 7,402,235 and 5,391,617, and European Patent 0638,611. Hydrogenated styrene-diene type viscosity index improvers can be prepared by copolymerizing styrene and butadiene and hydrogenating the unsaturated copolymer. The hydrogenated styrene-diene copolymer can be a linear block copolymer or a star. For examples of HSD copolymers as viscosity modifiers in lubricating oils, see U.S. Patents 4,116,917, 3,772,196, and 4,788,316.

[0048] Other properties of the lubricating oil composition of the present application The lubricating oil compositions of this application are generally of an SAE viscosity grade of either 0W-8, 0W-12, 0W-16, or 0W-20.

[0049] The lubricating oil compositions generally have a viscosity index of greater than about 200, or greater than about 205, or greater than about 210, or greater than about 220, or greater than about 240 up to about 270 or higher.

[0050] Lubricating oil compositions generally improve fuel economy. The degree of fuel economy improvement (FEI as described below) can vary depending on the particular lubricating oil composition, the engine used, and other factors. In some cases, the compositions described herein exhibit a fuel economy improvement (FEI) of at least about 1%, or at least about 1.5%, or at least about 2% up to 4% or more.

[0051] Other additives consistent with the ingredients and properties listed above may be added. Consistent with the components and properties of the lubricating oil composition described above, the lubricating oil composition may further include at least additives or modifiers (hereinafter referred to as "additives") that may impart or improve any desired properties of the lubricating oil composition. Any additive known to those skilled in the art may be used in the lubricating oil compositions disclosed herein. Some suitable additives are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition. London, Springer, (1996), and Leslie R. Rudnick, "Lubricant Additives: Chemistry and Applications," New York, Marcel Dekker (2003), both of which are incorporated herein by reference. In some embodiments, the additives may be selected from the group consisting of antioxidants, antiwear agents, detergents, rust inhibitors, demulsifiers, friction modifiers, multifunctional additives, viscosity index improvers, pour point depressants, antifoam agents, metal deactivators, dispersants, corrosion inhibitors, lubricity improvers, thermal stability improvers, anti-haze additives, icing inhibitors, pigments, markers, static dissipatives, biocides, and combinations thereof.

[0052] Particularly suitable combinations of additives include the detergent compositions as described above, including the above amounts of glycerol, dispersant additives such as ethylene carbonate post-treated bissuccinimides, anti-wear additives such as zinc dialkyldithiophosphates such as those derived from primary alcohols, and at least one highly overbased sulfonate detergent (e.g., highly overbased calcium sulfonate) and at least one non-sulfonate detergent (e.g., phenate detergent). The zinc dialkyldithiophosphates may be primary, secondary zinc dialkyldithiophosphates, or combinations thereof, and may be present at 3 wt. % or less (e.g., 0.1-1.5 wt. %, or 0.5-1.0 wt. %) of the lubricating oil composition. The dispersant, such as ethylene carbonate post-treated bissuccinimides, may be present at 0.1-10 wt. % (e.g., 0.5-8, 0.7-7, 0.7-6, 0.7-6, 0.7-5, 0.7-4 wt. %) based on the total weight of the lubricating oil composition.

[0053] Generally, the concentration of each of the additives in the lubricating oil composition, if used, may range from about 0.001% to about 10%, about 0.01% to about 5%, or about 0.1% to about 2.5% by weight based on the total weight of the lubricating oil composition. Additionally, the total amount of additives in the lubricating oil composition may range from about 0.001% to about 20%, about 0.01% to about 10%, or about 0.1% to about 5% by weight based on the total weight of the lubricating oil composition.

[0054] Anti-wear Agent Optionally, the lubricating oil compositions disclosed herein may contain one or more anti-wear agents. Anti-wear agents reduce wear of metal parts. Suitable anti-wear agents include metal dihydrocarbyl dithiophosphates, such as zinc dihydrocarbyl dithiophosphate (ZDDP), which has the following structure: Zn[SP(=S)(OR 1 )(OR 2 )]2 In the formula, R 1 and R 2R can be the same or different hydrocarbyl radicals having 1 to 18 (e.g., 2 to 12) carbon atoms, including radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl, and alicyclic radicals. 1 and R 2 Particularly preferred as groups are alkyl groups having 2 to 8 carbon atoms (e.g., the alkyl radical can be ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, 2-ethylhexyl). To obtain oil solubility, the total number of carbon atoms (i.e., R 1 +R 2 ) is at least 5. Thus, the zinc dihydrocarbyl dithiophosphate can include a zinc dialkyl dithiophosphate. The zinc dialkyl dithiophosphate is a primary, secondary zinc dialkyl dithiophosphate, or a combination thereof. The ZDDP can be present at 3 wt % or less (e.g., 0.1 to 1.5 wt %, or 0.5 to 1.0 wt %) of the lubricating oil composition.

[0055] Dispersants Optionally, the lubricating oil composition disclosed herein may further comprise a dispersant. Dispersants keep oil-insoluble materials suspended resulting from oxidation during engine operation, thus preventing flocculation and precipitation or deposition of sludge on metal parts. Dispersants useful herein include nitrogen-containing ashless (metal-free) dispersants known to be effective in reducing deposit formation when used in gasoline and diesel engines. Suitable dispersants include hydrocarbyl succinimides, hydrocarbyl succinamides, mixed esters / amides of hydrocarbyl-substituted succinic acids, hydroxyesters of hydrocarbyl-substituted succinic acids, and Mannich condensation products of hydrocarbyl-substituted phenols, formaldehyde, and polyamines. Also suitable are condensation products of polyamines and hydrocarbyl-substituted phenyl acids. Mixtures of these dispersants may also be used.

[0056] Basic nitrogen-containing ashless dispersants are well-known lubricating oil additives, and methods for their preparation are extensively described in the patent literature. Preferred dispersants are alkenyl succinimides and succinamides, where the alkenyl substituent is preferably long-chain, greater than 40 carbon atoms. These materials are easily made by reacting hydrocarbyl-substituted dicarboxylic acid materials with molecules containing amine functionality. Examples of suitable amines are polyamines, such as polyalkylene polyamines, hydroxy-substituted polyamines, and polyoxyalkylene polyamines. As known to those skilled in the art, dispersants may be post-treated (e.g., with boronating agents, ethylene carbonate, or cyclic carbonates). Nitrogen-containing ashless (metal-free) dispersants are basic and contribute to the TBN of the lubricating oil composition to which they are added without introducing additional sulfated ash. The dispersant may be present at 0.1 to 10 wt% (e.g., 0.5 to 8, 0.7 to 7, 0.7 to 6, 0.7 to 6, 0.7 to 5, 0.7 to 4 wt%) based on the actives level of the lubricating oil composition. Nitrogen from the dispersant is present at 0.0050 to greater than 0.30 wt% (e.g., 0.0050 to 0.10 wt%, 0.0050 to 0.080 wt%, 0.0050 to 0.060 wt%, 0.0050 to 0.050 wt%, 0.0050 to 0.040 wt%, 0.0050 to greater than 0.030 wt%) based on the weight of dispersant in the finished oil.

[0057] Antioxidants Optionally, the lubricating oil composition disclosed herein may further comprise an additional antioxidant that may reduce or prevent oxidation of the base oil. Any antioxidant known to those skilled in the art may be used in the lubricating oil composition. Non-limiting examples of suitable antioxidants include amine-based antioxidants (e.g., alkyldiphenylamines, phenyl-alpha-naphthylamines, alkyl or aralkyl substituted phenyl-alpha-naphthylamines, alkylated p-phenylenediamines, tetramethyl-diaminodiphenylamines, etc.), phenolic antioxidants (e.g., 2-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2, 6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 4,4'-methylenebis-(2,6-di-tert-butylphenol), 4,4'-thiobis(6-di-tert-butyl-o-cresol), etc.), sulfur-based antioxidants (e.g., dilauryl-3,3'-thiodipropionate, sulfurized phenolic antioxidants, etc.), phosphorus-based antioxidants (e.g., phosphites, etc.), zinc dithiophosphates, oil-soluble copper compounds, and combinations thereof. The amount of antioxidant can vary from about 0.01 wt.% to about 10 wt.%, from about 0.05 wt.% to about 5 wt.%, or from about 0.1 wt.% to about 3 wt.%, based on the total weight of the lubricating oil composition. Some suitable antioxidants are described in Leslie R. Rudnick, “Lubricant Additives: Chemistry and Applications,” New York. Marcel Dekker, Chapter 1, pages 1-28 (2003), which is incorporated herein by reference. Friction modifiers As mentioned above, the lubricating oil compositions disclosed herein are generally substantially free of friction modifiers. "Substantially free" is defined above to include less than about 50 ppm. In some examples, the lubricating oil compositions disclosed herein include less than about 25 ppm or even 0 ppm of friction modifiers. Friction modifiers that are typically excluded from the lubricating oil compositions disclosed herein are aliphatic carboxylic acids; derivatives of aliphatic carboxylic acids (e.g., alcohols, esters, borated esters, amides, metal salts, etc.); mono-, di-, or tri-alkyl substituted phosphoric or phosphonic acids; derivatives of mono-, di-, or tri-alkyl substituted phosphoric or phosphonic acids (e.g., esters, amides, metal salts, etc.); mono-, di-, or tri-alkyl substituted amines; mono- or di-alkyl substituted amides; alkoxylated fatty amines; borated fatty epoxides; aliphatic phosphites, aliphatic epoxides, aliphatic amines, borated alkoxylated fatty amines, metal salts of fatty acids, fatty acid amides, glycerol esters, borated glycerol esters; aliphatic imidazolines; C4-C 75 , or C6~C 24 , or C6~C 20 and a nitrogen-containing compound selected from the group consisting of ammonia and alkanolamines; molybdenum dithiocarbamates (MoDTC); molybdenum dithiophosphates (MoDTP); molybdenum amines; molybdenum alcoholates; and molybdenum alcohol-amides.

[0058] Pour Point Depressants The lubricating oil compositions disclosed herein may optionally include a pour point depressant that may reduce the pour point of the lubricating oil composition. Any pour point depressant known to one of ordinary skill in the art may be used in the lubricating oil composition. Non-limiting examples of suitable pour point depressants include polymethacrylates, alkyl acrylate polymers, alkyl methacrylate polymers, di(tetra-paraffin phenol) phthalate, condensates of tetra-paraffin phenol, condensates of chlorinated paraffins and naphthalene, and combinations thereof. In some embodiments, the pour point depressant includes ethylene-vinyl acetate copolymers, condensates of chlorinated paraffins and phenols, polyalkylstyrenes, and the like. The amount of pour point depressant may vary from about 0.01 wt % to about 10 wt %, from about 0.05 wt % to about 5 wt %, or from about 0.1 wt % to about 3 wt %, based on the total weight of the lubricating oil composition. Some suitable pour point depressants are described in Mortier et al., “Chemistry and Technology of Lubricants,” 2nd Edition, London, Springer, Chapter 6, pages 187-189 (1996), and Leslie R. Rudnick, “Lubricant Additives: Chemistry and Applications,” New York, Marcel Dekker, Chapter 11, pages 329-354 (2003), both of which are incorporated herein by reference.

[0059] Demulsifier The lubricating oil composition disclosed herein may optionally include a demulsifier that may promote oil-water separation in the lubricating oil composition exposed to water or steam. Any demulsifier known to those skilled in the art may be used in the lubricating oil composition. Non-limiting examples of suitable demulsifiers include anionic surfactants (e.g., alkyl-naphthalene sulfonates, alkylbenzene sulfonates, etc.), nonionic alkoxylated alkylphenol resins, polymers of alkylene oxides (e.g., polyethylene oxide, polypropylene oxide, block copolymers of ethylene oxide, propylene oxide, etc.), esters of oil-soluble acids, polyoxyethylene sorbitan esters, and combinations thereof. The amount of demulsifier may vary from about 0.01 wt.% to about 10 wt.%, from about 0.05 wt.% to about 5 wt.%, or from about 0.1 wt.% to about 3 wt.%, based on the total weight of the lubricating oil composition. Some suitable demulsifiers are described in Mortier et al., “Chemistry and Technology of Lubricants,” 2nd Edition. London, Springer, Chapter 6, pages 190-193 (1996), which is incorporated herein by reference.

[0060] Foam inhibitor The lubricating oil compositions disclosed herein may optionally include an antifoaming agent or defoamer that may break down foam in the oil. Any antifoaming agent or defoamer known to one of ordinary skill in the art may be used in the lubricating oil composition. Non-limiting examples of suitable defoamers include silicone oils or polydimethylsiloxanes, fluorosilicones, alkoxylated aliphatic acids, polyethers (e.g., polyethylene glycols), branched polyvinyl ethers, alkyl acrylate polymers, alkyl methacrylate polymers, polyalkoxyamines, and combinations thereof. In some embodiments, the defoamer comprises glycerol monostearate, polyglycol palmitate, trialkyl monothiophosphate, esters of sulfonated ricinoleic acid, benzoylacetone, methyl salicylate, glycerol monooleate, or glycerol dioleate. The amount of defoamer may vary from about 0.01% to about 5% by weight, from about 0.05% to about 3% by weight, or from about 0.1% to about 1% by weight based on the total weight of the lubricating oil composition. Some suitable antifoaming agents are described in Mortier et al., “Chemistry and Technology of Lubricants,” 2nd Edition, London, Springer, Chapter 6, pages 190-193 (1996), which is incorporated herein by reference.

[0061] Corrosion Inhibitors The lubricating oil composition disclosed herein may optionally include a corrosion inhibitor that may reduce corrosion. Any corrosion inhibitor known to a person skilled in the art may be used in the lubricating oil composition. Non-limiting examples of suitable corrosion inhibitors include half esters or amides of dodecyl succinic acid, phosphate esters, thiophosphates, alkyl imidazolines, sarcosines, and combinations thereof. The amount of corrosion inhibitor may vary from about 0.01 wt.% to about 5 wt.%, from about 0.05 wt.% to about 3 wt.%, or from about 0.1 wt.% to about 1 wt.%, based on the total weight of the lubricating oil composition. Some suitable corrosion inhibitors are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London, Springer, Chapter 6, pages 193-196 (1996), which is incorporated herein by reference.

[0062] Extreme Pressure Agent The lubricating oil composition disclosed herein may optionally contain an extreme pressure (EP) agent that can prevent the sliding metal surfaces from seizing under extreme pressure conditions. Any extreme pressure agent known to those skilled in the art can be used in the lubricating oil composition. In general, an extreme pressure agent is a compound that can chemically combine with metal to form a surface film that prevents the welding of asperities on opposing metal surfaces under high load. Non-limiting examples of suitable extreme pressure agents include sulfurized animal or vegetable fats or oils, sulfurized animal or vegetable fatty acid esters, fully or partially esterified esters of trivalent or pentavalent acids of phosphorus, sulfurized olefins, dihydrocarbyl polysulfides, sulfurized Diels-Alder adducts, sulfurized dicyclopentadiene, sulfurized or co-sulfurized mixtures of fatty acid esters and monounsaturated olefins, co-sulfurized blends of fatty acids, fatty acid esters, and alpha-olefins, functionally substituted dihydrocarbyl polysulfides, thia-aldehydes, thia-ketones, epithio compounds, sulfur-containing acetal derivatives, co-sulfurized blends of terpenes and acyclic olefins, and polysulfide olefin products, amine salts of phosphates or thiophosphates, and combinations thereof. The amount of extreme pressure agent may vary from about 0.01% to about 5% by weight, from about 0.05% to about 3% by weight, or from about 0.1% to about 1% by weight based on the total weight of the lubricating oil composition. Some suitable extreme pressure agents are described in Leslie R. Rudnick, “Lubricant Additives: Chemistry and Applications,” New York, Marcel Dekker, Chapter 8, pages 223-258 (2003), which is incorporated herein by reference.

[0063] Rust inhibitor The lubricating oil composition disclosed herein may optionally include a rust inhibitor that can inhibit corrosion of ferrous metal surfaces. Any rust inhibitor known to those skilled in the art may be used in the lubricating oil composition. Non-limiting examples of suitable rust inhibitors include oil-soluble monocarboxylic acids (e.g., 2-ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, cerotic acid, etc.), oil-soluble polycarboxylic acids (e.g., those derived from tall oil fatty acids, oleic acid, linoleic acid, etc.), alkenyl succinic acids in which the alkenyl group contains 10 or more carbon atoms (e.g., tetrapropenyl succinic acid, tetradecenyl succinic acid, hexadecenyl succinic acid, etc.); long chain alpha, omega-dicarboxylic acids having molecular weights in the range of 600 to 3000 daltons, and combinations thereof. The amount of the rust inhibitor can vary from about 0.01% to about 10% by weight, from about 0.05% to about 5% by weight, or from about 0.1% to about 3% by weight, based on the total weight of the lubricating oil composition.

[0064] Other non-limiting examples of suitable rust inhibitors include non-ionic polyoxyethylene surfactants such as polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene octylstearyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate. Further non-limiting examples of suitable rust inhibitors include stearic acid and other fatty acids, dicarboxylic acids, metal soaps, fatty acid amine salts, metal salts of heavy sulfonic acids, partial carboxylic acid esters of polyhydric alcohols, and phosphoric acid esters.

[0065] Multifunctional Additives In some embodiments, the lubricating oil composition comprises at least a multifunctional additive. Some non-limiting examples of suitable multifunctional additives include sulfurized oxymolybdenum dithiocarbamates, sulfurized oxymolybdenum organophosphorodithioates, oxymolybdenum monoglycerides, oxymolybdenum diethylate amides, amine-molybdenum complex compounds, and sulfur-containing molybdenum complex compounds.

[0066] Viscosity modifier In certain embodiments, the lubricating oil composition includes at least a viscosity modifier. Some non-limiting examples of suitable viscosity modifiers include polymethacrylate type polymers, ethylene-propylene copolymers, styrene-isoprene copolymers, hydrated styrene-isoprene copolymers, polyisobutylene, and dispersant type viscosity modifiers.

[0067] metal deactivator In some embodiments, the lubricating oil composition includes at least a metal deactivator. Some non-limiting examples of suitable metal deactivators include disalicylidene propylene diamine, triazole derivatives, thiadiazole derivatives, and mercaptobenzimidazole.

[0068] Additive Concentrate Formulation The additives disclosed herein may be in the form of an additive concentrate having multiple additives. The additive concentrate may include a suitable diluent, such as a hydrocarbon oil of suitable viscosity. Such a diluent may be selected from the group consisting of natural oils (e.g., mineral oils), synthetic oils, and combinations thereof. Some non-limiting examples of mineral oils include paraffin-based oils, naphthene-based oils, asphalt-based oils, and combinations thereof. Some non-limiting examples of synthetic base oils include polyolefin oils (especially hydrogenated alpha-olefin oligomers), alkylated aromatics, polyalkylene oxides, aromatic ethers, and carboxylic acid esters (especially diester oils), and combinations thereof. In some embodiments, the diluent is a light hydrocarbon oil (both natural or synthetic). In general, the diluent oil may have a viscosity of about 13 centistokes to about 35 centistokes at 40°C.

[0069] In general, it is desirable for the diluent to readily solubilize lubricating oil soluble additives and provide an oil additive concentrate that is readily soluble in the lubricating base oil stock or fuel, and also not introduce any undesirable properties, including, for example, high volatility, high viscosity, and impurities such as heteroatoms, into the lubricating base oil stock and, ultimately, into the finished lubricating oil or fuel.

[0070] The present application further provides an oil soluble additive concentrate composition comprising an inert diluent and from 2.0% to 90% by weight, preferably from 10% to 50% by weight, based on the total concentrate, of an oil soluble additive composition according to the present application.

[0071] Lubricating oil compositions containing the additives described above may be used in a method for improving fuel economy in an internal combustion engine, the method comprising lubricating the engine with the lubricating oil composition containing the additive and operating the engine.

[0072] The following examples are provided to illustrate the embodiments and are not intended to limit the present application to the specific embodiments described. Unless otherwise indicated, all parts and percentages are by weight. All numerical values ​​are approximate. When numerical ranges are given, it should be understood that embodiments outside the ranges stated may still fall within the scope of the present application. The specific details described in each example should not be construed as necessary features. EXAMPLES

[0073] The following examples are intended for illustrative purposes only and are not limiting in scope in any way.

[0074] Example 1 An SAE 0W-8 lubricating oil was prepared by blending the following components together with 2.5 cSt Group III base oil: A) 3.5% by weight succinimide dispersant B) A 1700 ppm (based on calcium content) overbased calcium sulfonate detergent having a TBN of 410 mg KOH / g. C) 750 ppm (based on phosphorus content) of secondary ZnDTP D) 1.0% by weight of a phenolic antioxidant E) 7.1% by weight of comb-type PMA viscosity modifier F) 5 ppm of silicon-based antifoam agent The lubricating oil composition of Example 1 had a KV100 of 4.34 cSt, a KV40 of 13.43, and a viscosity index of 272.

[0075] Comparative Example 1 The lubricant of Comparative Example 1 was formulated identically to Example 1, except that the comb-type PMA viscosity modifier was replaced with 3.78 wt.% of a linear dispersion-type PMA viscosity modifier. The lubricant composition of Comparative Example 1 had a KV100 of 4.80 cSt, a KV40 of 17.12, and a viscosity index of 226.

[0076] Comparative Example 2 The lubricant of Comparative Example 2 was formulated identically to Example 1, except that the comb type PMA viscosity modifier was replaced with 5.78 wt.% of an olefin copolymer viscosity modifier. 0.40 wt.% of a pour point depressant was also added. The lubricant composition of Comparative Example 2 had a KV100 of 4.74 cSt, a KV40 of 19.65, and a viscosity index of 171.

[0077] Comparative Example 3 The lubricant of Comparative Example 3 was formulated identically to Example 1, except that the calcium sulfonate detergent was replaced with an equal amount (based on calcium) of a calcium salicylate detergent having a TBN of 410 mg KOH / g. The lubricant composition of Comparative Example 3 had a KV100 of 4.37 cSt, a KV40 of 13.48, and a viscosity index of 275.

[0078] Comparative Example 4 Comparative Example 4 lubricating oil was formulated identically to Example 1, except that 70 ppm (in terms of boron) of a boronated ester friction modifier was further blended into the composition.

[0079] Comparative Example 5 Comparative Example 5 lubricant was formulated identically to Example 1, except that 660 ppm (in terms of molybdenum) of MoDTC was further blended into the composition.

[0080] Example 2 The lubricant of Example 2 was formulated identically to Example 1, except that 4 cSt Group III base oil was substituted to produce a lubricant composition having an SAE viscosity grade of 0W-16. The lubricant composition of Example 2 had a KV100 of 6.29 cSt, a KV40 of 26.02, and a viscosity index of 208.

[0081] Comparative Example 6 The lubricant of Comparative Example 6 was formulated identically to Example 2, except that the calcium sulfonate detergent was replaced with an equal amount (based on calcium) of a calcium salicylate detergent having a TBN of 410 mg KOH / g. The lubricant composition of Comparative Example 6 had a KV100 of 6.32 cSt, a KV40 of 25.90, and a viscosity index of 211.

[0082] Fuel economy test for Toyota 2ZR-FXE (JASO M366) The above lubricating oil compositions were tested for their fuel economy performance in a gasoline motor engine (Toyota 2ZR-FXE 1.8L L-4). Detailed configuration of the test equipment and conditions can be found in SAE paper 2019-01-2296 Jikuya, H., Mori, S., Yamamori, K., and Hirano, S., “Development of Firing Fuel Economy Engine Dyno Test Procedure for JASO Ultra Low Viscosity Engine Oil Standard (JASO GLV-1),” SAE Technical Paper 2019-01-2296, 2019, which is incorporated herein by reference. The test oils are preconditioned at an oil temperature of 88° C. for 10 hours in an engine operated at 1350 rpm. The fuel consumption of the test oils is measured over a 4-hour period and compared against the fuel consumption of a baseline calibration (BC) oil.

[0083] The BC oil used in the above test method is different from the JASO BC oil, and the viscosity measurement values ​​of the BC oil are shown below. [Table 1]

[0084] The Fuel Economy Improvement (FEI) for each candidate oil tested is calculated as the relative improvement (% change) compared to the average of the two BC oils shown below. A higher FEI value indicates better overall fuel economy performance.

number

number

[0085] [Table 2]

[0086] The FEI results of Example 1 vs. Comparative Examples 1 and 2 show that comb PMA provides better fuel economy compared to linear dispersion PMA or OCP viscosity modifiers. As shown by Comparative Example 3, replacement of sulfonate with salicylate detergent also resulted in lower fuel economy values. Furthermore, the combination of sulfonate detergent and comb PMA in the absence of any additional FM outperforms Comparative Example 4, which contains a boron-based friction modifier. It was also demonstrated that the combination of comb PMA and sulfonate without added FM (Example 2 vs. Comparative Example 6) is effective in higher viscosity formulations.

[0087] It will be understood that various modifications may be made to the embodiments disclosed herein. Thus, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. For example, the functions described and implemented above for operation are for illustrative purposes only. Other arrangements and methods may be implemented by those skilled in the art without departing from the scope and spirit of the present application. Moreover, those skilled in the art will envision other modifications within the scope and spirit of the appended claims.

Claims

1. 1. A lubricating oil composition for an internal combustion engine, comprising: a) a major amount of an oil of lubricating viscosity; b) an alkaline earth metal sulfonate detergent providing 1200 to 2200 ppm metal to said lubricating oil composition; c) a comb type polymethacrylate viscosity modifier having a PSSI of less than 15; the lubricating oil composition has an SAE viscosity grade of 0W-8, 0W-12, 0W-16, or 0W-20; The lubricating oil composition, wherein the lubricating oil composition is substantially free of friction modifiers.

2. 10. The lubricating oil composition of claim 1, wherein the lubricating oil composition has a viscosity index greater than 200.

3. 10. The lubricating oil composition of claim 1, wherein the composition comprises less than 50 ppm of a friction modifier.

4. 10. The lubricating oil composition of claim 1, wherein the composition comprises less than 25 ppm of a friction modifier.

5. 10. The lubricating oil composition of claim 1, wherein the composition contains 0 ppm of friction modifiers.

6. 10. The lubricating oil composition of claim 1, wherein the composition exhibits a fuel economy improvement (FEI) of at least about 1%.

7. 10. The lubricating oil composition of claim 1, wherein the composition exhibits a fuel economy improvement (FEI) of at least about 2%.

8. 2. The lubricating oil composition of claim 1, wherein the lubricating oil composition has an SAE viscosity grade of 0W-8.

9. 2. The lubricating oil composition of claim 1, wherein the lubricating oil composition has an SAE viscosity grade of 0W-12.

10. 2. The lubricating oil composition of claim 1, wherein the lubricating oil composition has an SAE viscosity grade of 0W-16.

11. The lubricating oil composition of claim 1, wherein the lubricating oil composition has an SAE viscosity grade of 0W-20.

12. 2. The lubricating oil composition of claim 1, wherein the alkaline earth metal sulfonate detergent is a magnesium sulfonate detergent, a calcium sulfonate detergent, or a mixture thereof.

13. 1. A method for improving fuel economy in an internal combustion engine, comprising: a) a major amount of an oil of lubricating viscosity; b) an alkaline earth metal sulfonate detergent providing 1200 to 2200 ppm metal to the lubricating oil composition; c) a comb type polymethacrylate viscosity modifier having a PSSI of less than 15; the lubricating oil composition has an SAE viscosity grade of 0W-8, 0W-12, 0W-16, or 0W-20; The method, wherein the lubricating oil composition is substantially free of friction modifiers.

14. The method of claim 13 , wherein the lubricating oil composition has a viscosity index greater than 200.

15. The method of claim 13, wherein the composition comprises less than 50 ppm of a friction modifier.

16. The method of claim 13, wherein the composition comprises less than 25 ppm of a friction modifier.

17. The method of claim 13, wherein the composition comprises 0 ppm of friction modifiers.

18. 14. The method of claim 13, wherein the composition exhibits a fuel economy improvement (FEI) of at least about 1%.

19. 14. The method of claim 13, wherein the composition exhibits a fuel economy improvement (FEI) of at least about 2%.

20. The method of claim 13, wherein the lubricating oil composition has an SAE viscosity grade of 0W-8.

21. The method of claim 13, wherein the lubricating oil composition has an SAE viscosity grade of 0W-12.

22. The method of claim 13, wherein the lubricating oil composition has an SAE viscosity grade of 0W-16.

23. The method of claim 13, wherein the lubricating oil composition has an SAE viscosity grade of 0W-20.

24. The method of claim 13, wherein the alkaline earth metal sulfonate detergent is a magnesium sulfonate detergent, a calcium sulfonate detergent, or a mixture thereof.

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