Marine diesel engine lubricating oil composition

Abstract

A marine diesel engine lubricating oil composition comprising (a) at least 40% by weight of an oil of lubricating viscosity having a kinematic viscosity at 100 DEG C of from 4.0 to less than 8.5 mm2 / s; and (b) one or more olefin copolymers having a number average molecular weight of from 30,000 to 120,000. The marine diesel engine lubricating oil composition has a TBN of greater than 30 mg KOH / g. The marine diesel engine lubricating oil composition is a single-stage lubricating oil composition which meets the requirements of the SAE J300 standard revised in January 2015 on SAE 30, SAE 40, SAE 50 or SAE 60 single-stage lubricating oil.

Description

Technical Field

[0001] The present disclosure relates to lubricating oil compositions, and more particularly, to the use of light neutral oils and olefin copolymer thickeners in marine lubricating oil compositions. Background Art

[0002] This section is intended to introduce the reader to various aspects of the technology that may be related to various aspects of the present disclosure described and / or claimed below. It is believed that this discussion helps to provide the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Therefore, it should be understood that these statements should be interpreted from this perspective, rather than as an admission of prior art.

[0003] Marine diesel internal combustion engines can be generally classified as low-speed, medium-speed or high-speed engines. Low-speed diesel engines are unique in size and method of operation. These engines are quite large and are usually operated in the range of about 60 revolutions per minute (rpm) to 200rpm. Low-speed diesel engines operate with a two-stroke cycle, and are generally direct-coupled and direct-reversed engines of a "crosshead" structure, with a diaphragm and one or more stuffing boxes, which separate the power cylinder from the crankcase to prevent combustion products from entering the crankcase and mixing with the crankcase oil. Marine two-stroke diesel engine cylinder lubricants must meet performance requirements in order to meet the harsh working conditions required for more modern larger bore engines, which operate at significantly changing outputs, loads and temperatures of cylinder liners. The complete separation of the crankcase from the combustion zone causes those skilled in the art to lubricate the combustion chamber and crankcase with different lubricating oils, which are respectively referred to as cylinder lubricants and system oils. Marine cylinder lubricants and system oils are subject to their own unique requirements.

[0004] In a two-stroke crosshead engine, the cylinders are lubricated on a gross loss basis, with cylinder oil being sprayed on each cylinder individually through lubricators positioned around the cylinder liners. The cylinder lubricant is not recirculated, and is burned with the fuel. The cylinder lubricant needs to provide a strong film between the cylinder liner and the piston ring, for adequate lubrication of the cylinder wall to prevent wear, be thermally stable so that the lubricant does not form deposits on the hot surfaces of the piston and piston rings, and be able to neutralize sulfur-based acidic combustion products. In contrast to the cylinder lubricant, the system oil is not exposed to the combustion chamber where the fuel is burned, and is formulated to last as long as possible to maximize the life of the oil.

[0005] Medium speed engines are typically operated in the range of about 250 rpm to 1100 rpm and operate in a four-stroke cycle. These engines typically have a trunk piston design. In a trunk piston engine, in contrast to a crosshead engine, a single lubricant is used to lubricate all areas of the engine. Therefore, trunk piston engine oils have unique requirements. The key lubricant performance parameters for operating a trunk piston engine include deposit control of the piston cooling oil cavity and piston ring pack, oxidation and viscosity increase control, demulsification performance, and sludge control. For marine residual fuel operation, these performance parameters are almost completely driven by asphaltene contamination from marine residual fuel.

[0006] Recent health and environmental issues have led to regulations requiring the use of lower sulfur fuels to operate marine diesel engines. As a result, manufacturers are now designing marine diesel engines for use with a variety of fuels, including residual-free gas fuels (e.g., compressed or liquefied natural gas), high-quality distillate fuels, to poorer quality intermediate fuels or heavy fuels, such as marine residual fuels, which typically have higher sulfur and higher asphaltene content. For residual-free fuel operation, the fuel does not contain significant asphaltenes present in the fuel and contains much lower sulfur levels. When the lower sulfur fuel is burned, less acid is formed in the combustion chamber.

[0007] One of the main characteristics of lubricants that helps protect marine diesel engines is the lubricant film "thickness", i.e., viscosity. Lubricants used to lubricate marine diesel internal combustion engines have high viscosity industry requirements due to low operating speeds and high loads, and are typically high viscosity single grades (i.e., lubricants that exhibit little or no viscosity index improvement properties) of SAE 30, SAE 40, SAE 50 or SAE 60 viscosity grades. Because hydrocracking causes viscosity loss of base stocks, marine oils cannot usually be formulated with hydrocracked base stocks alone. In order to achieve suitable lubricant film thickness, conventional marine formulations typically include large amounts of heavy neutral oils and / or high viscosity bright stock in marine lubricants, which are highly refined and dewaxed high viscosity base oils, and are produced from residual oil stocks or bottoms.

[0008] However, reliance on bright stock is not always desirable due to the presence of oxidatively unstable aromatic compounds. Furthermore, the availability of bright stock is decreasing, resulting in large uses, such as those for marine engines, requiring alternative solutions to impart the desired viscosity in lubricants. In view of the increasing severity of changes brought about by design changes in modern marine engines, changing requirements related to fuel quality, and declining bright stock capacity, there is a continuing need for improved marine diesel engine lubricant formulation technology that provides improved performance while achieving the high viscosity required for marine lubricants. Summary of the invention

[0009] An overview of certain embodiments disclosed herein is as follows. It should be understood that these aspects presented are only intended to provide the reader with a brief overview of these specific embodiments, and these aspects are not intended to limit the scope of the present disclosure. In fact, the present disclosure may encompass a number of aspects that may not be described below.

[0010] Generally, in one aspect, the present disclosure relates to a marine diesel engine lubricating oil composition comprising (a) at least 40 wt% of an oil of lubricating viscosity having a kinematic viscosity at 100°C of 4.0 to less than 8.5 mm2 / s; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000. The marine diesel engine lubricating oil composition has a TBN greater than 30 mg KOH / g and is a monograde lubricating oil composition that meets the requirements of the SAE J300 specification revised in January 2015 for SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oils.

[0011] In another aspect, the present disclosure relates to a method for thickening a lubricating oil composition in a marine diesel internal combustion engine. The method comprises adding a lubricating oil composition to the engine, the lubricating oil composition comprising: (a) at least 40% by weight of an oil of lubricating viscosity having a kinematic viscosity of 4.0 to less than 8.5 mm2 / s at 100°C; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000. The marine diesel engine lubricating oil composition has a TBN greater than 30 mg KOH / g and is a monograde lubricating oil composition that meets the requirements of the SAE J300 specification revised in January 2015 for SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oils.

[0012] In a further aspect, the present disclosure relates to a method for controlling deposit formation in an internal combustion engine. The method comprises operating the internal combustion engine with a lubricating oil composition. The lubricating oil composition comprises: (a) at least 40 wt. % of an oil of lubricating viscosity having a kinematic viscosity of 4.0 to less than 8.5 mm2 / s at 100°C; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000. The marine diesel engine lubricating oil composition has a TBN greater than 30 mg KOH / g and is a monograde lubricating oil composition that meets the requirements of the SAE J300 specification revised in January 2015 for SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oils. DETAILED DESCRIPTION

[0013] definition

[0014] In this specification, the following words and expressions if and when used have the following ascribed meanings.

[0015] "Major amount" means greater than 40% by weight of the composition.

[0016] "A small amount" means less than 40% by weight of the composition.

[0017] "Marine residual fuel" refers to a material combustible in large marine engines having a carbon residue of at least 2.5 wt % (e.g., at least 5 wt %, or at least 8 wt %) (relative to the total weight of the fuel) (as defined in the International Organization for Standardization (ISO) 10370), a viscosity greater than 14.0 cSt at 50°C, such as the marine residual fuel defined in the International Organization for Standardization specification ISO 8217:2005, "Petroleum products--Fuels (class F)--Specifications of marine fuels", the contents of which are incorporated herein in their entirety.

[0018] "Residual fuel" refers to a fuel that meets the specifications for residual marine fuels as set out in the ISO 8217:2010 international standard. "Low sulfur marine fuel" refers to a fuel that meets the specifications for residual marine fuels as set out in the ISO 8217:2010 specification, which additionally has about 1.5 wt% or less, or even about 0.5 wt% or less, of sulfur relative to the total weight of the fuel.

[0019] "Distillate fuel" refers to a fuel that meets the specifications for distillate marine fuels as set forth in the ISO 8217:2010 international standard. "Low sulfur distillate fuel" refers to a fuel that meets the specifications for distillate marine fuels as set forth in the ISO 8217:2010 international standard, which additionally has about 0.1 wt% or less, or even about 0.005 wt% or less, of sulfur relative to the total weight of the fuel.

[0020] "Low sulfur fuel" refers to fuel having about 1.5 wt% or less, or even about 1.0 wt% or less, or even 0.5 wt% or less, or even 0.1 wt% or less sulfur relative to the total weight of the fuel.

[0021] A "high sulfur fuel" is a fuel having greater than 1.5 weight percent sulfur relative to the total weight of the fuel.

[0022] The term "on an active basis" refers to additive materials that are not diluent oils or solvents.

[0023] As used in this specification and claims, "α-olefin" refers to an olefin having a carbon-carbon double bond between the first and second carbon atoms of the longest continuous chain of carbon atoms. The term "α-olefin" includes both straight and branched α-olefins, unless expressly stated otherwise. In the case of branched α-olefins, the branches may be at the 2-position (vinylidene) and / or 3-position or higher relative to the olefin double bond. Whenever used in this specification and claims, the term "vinylidene" refers to an α-olefin having a branch at the 2-position relative to the olefin double bond. α-olefins are almost always a mixture of isomers, and are usually also a mixture of compounds having a range of carbon numbers. Low molecular weight α-olefins, such as C6, C8, C 10 , C 12 and C 14 Alpha olefins are almost exclusively 1-olefins. Higher molecular weight olefin fractions such as C 16 -C 18 or C 20 -C 24 There is an increased proportion of double bonds isomerized to internal or vinylidene positions.

[0024] "Normal alpha olefin" (NAO) refers to a linear aliphatic monoolefin having a carbon-carbon double bond between a first carbon atom and a second carbon atom. It should be noted that "normal alpha olefin" is not synonymous with "linear alpha olefin" because the term "linear alpha olefin" can include linear olefinic compounds having a double bond between a first carbon atom and a second carbon atom.

[0025] "Isomerized olefins" or "isomerized normal alpha olefins" refer to olefins obtained by isomerizing olefins. Typically, isomerized olefins have double bonds at different positions than the starting olefins from which they are derived, and may also have different properties.

[0026] "Isomerization level (I)" refers to the isomerization level measured by NMR methods. The isomerization level of olefins is determined by hydrogen-1 (1H) NMR. NMR spectra were obtained on a Bruker Ultrashield Plus 400 in chloroform-di at 400 MHz using TopSpin 3.2 spectral processing software. The isomerization level represents the relative amount of methyl groups (-CH3) (chemical shift 0.30-1.01 ppm) attached to methylene backbone groups (-CH2-) (chemical shift 1.01-1.38 ppm) and is defined by equation (I) = m / (m+n), where m is the NMR integral of methyl groups with chemical shifts between 0.30 ± 0.03 and 1.01 ± 0.03 ppm, and n is the NMR integral of methylene groups with chemical shifts between 1.01 ± 0.03 and 1.38 ± 0.10 ppm.

[0027] The term "Total Base Number" or "TBN" or "BN" refers to the level of alkalinity in an oil sample according to ASTM Standard No. D2896 or equivalent procedures, which indicates the ability of the composition to continue to neutralize corrosive acids. The test measures the change in conductivity, and the results are expressed as mgKOH / g (milligram equivalents of KOH required to neutralize 1 gram of product). Therefore, a high TBN reflects a strongly overbased product, and therefore a higher base reserve for neutralizing acids. Where TBN values ​​are introduced herein, it is understood that they are expressed in units of mgKOH / g.

[0028] "Overbased" is used to describe metal detergents in which the ratio of the number of equivalents of metal moieties to the number of equivalents of acid moieties is greater than one.

[0029] "Soap" means a neutral detergent compound which contains an approximately stoichiometric amount of a metal to effect neutralization of one or more acidic groups present in the organic acid used to prepare the detergent.

[0030] "Metal" refers to an alkali metal, an alkaline earth metal or a mixture thereof. When an alkali metal is used, the alkali metal is lithium, sodium or potassium. When an alkaline earth metal is used, the alkaline earth metal may be selected from the group consisting of calcium, barium, magnesium and strontium. Calcium and magnesium are preferred.

[0031] Unless otherwise expressly stated, "weight percent" (wt%) refers to the percentage of the total weight of the entire composition by which the listed component, compound or substituent is present. Unless otherwise stated, all reported percentages are based on the weight percent of the active ingredient (i.e., without regard to carrier or diluent oil). The diluent oil used in lubricant additives can be any suitable base oil (e.g., Group I base oil, Group II base oil, Group III base oil, Group IV base oil, Group V base oil or mixtures thereof). The weight percents representing the combination of the ingredients and the carrier or diluent oil are referred to as the weight percents "as is".

[0032] The term "sulfated ash content" refers to the amount of metal-containing additives (eg, calcium, magnesium, molybdenum, zinc) in a lubricating oil composition, and is generally measured according to ASTM D874, which is incorporated herein by reference.

[0033] Lubricating oil composition

[0034] It has surprisingly been found that replacing (e.g., completely replacing) heavy neutral base oils and bright stock with a combination of a lighter neutral base stock and an olefin copolymer thickener in a marine lubricant provides a lubricating oil composition that exhibits improved resistance to deposit formation and oxidation stability in engines operating under various load conditions, such as high load conditions, while achieving suitable lubricating oil viscosity.

[0035] In certain embodiments, the lubricating oil composition of the present disclosure is a marine diesel engine lubricating oil. In such embodiments, the lubricating oil composition comprises (a) at least 40 wt% of an oil of lubricating viscosity having a relative humidity of 4.0 mm at 100°C. 2 / s to less than 8.5mm 2 / s kinematic viscosity; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000; wherein the lubricating oil composition is a monograde lubricating oil composition that meets the requirements of the SAE J300 specification revised in January 2015 for 30, 40, 50 or 60 monograde engine oils and has a TBN greater than 30 mg KOH / g, as determined by ASTM D2896. The kinematic viscosity of the oil having lubricating viscosity may correspond to the viscosity of a light neutral oil.

[0036] The lubricating oil composition may be a monograde lubricating oil composition that meets the requirements of the SAE J300 specification for 30, 40, 50 or 60 monograde engine oils as revised in January 2015. SAE 30 oils have a viscosity of 9.3 to <12.5 mm at 100°C. 2 / s kinematic viscosity. SAE 40 oil has a kinematic viscosity of 12.5 to <16.3 mm at 100°C. 2 / s kinematic viscosity. SAE 50 oil has a kinematic viscosity of 16.3 to <21.9 mm at 100°C. 2 / s kinematic viscosity. SAE 60 oil has a kinematic viscosity of 21.9 to <26.1 mm at 100°C. 2 / s kinematic viscosity.

[0037] In some embodiments, the lubricating oil composition is suitable for use as a marine cylinder lubricant (MCL).The marine cylinder lubricant of the present disclosure is manufactured according to SAE 30, SAE 40, SAE 50 or SAE 60 single grade specifications to provide a sufficiently thick lubricant film on the cylinder liner wall at high temperatures.

[0038] In addition to providing a sufficient degree of lubricity, one of the main functions of a marine cylinder lubricant is to neutralize the sulfur-based acidic components of the burning sulfur-containing fuel. This neutralization is usually achieved by including an alkaline substance such as an overbased metal detergent. The neutralizing ability of an oil is characterized by its alkalinity and measured by its total base number (TBN). Typically, the sulfur-containing fuels used to operate marine diesel engines create a need for a marine cylinder lubricant with high detergency and neutralizing ability, even if the oil is only exposed to heat and other stresses for a short period of time.

[0039] To allow for adequate neutralization and detergency, the marine diesel engine cylinder lubricant of the present disclosure has a TBN of at least 30 mg KOH / g. By way of example, the TBN may be in the range of greater than 30 to 200 mg KOH / g, or greater than 30 to 150 mg KOH / g, or greater than 30 to 120 mg KOH / g, greater than 30 to 100 mg KOH / g, greater than 30 to 80 mg KOH / g, 60 to 200 mg KOH / g, 60 to 150 mg KOH / g, 60 to 120 mg KOH / g, 60 to 100 mg KOH / g, 60 to 80 mg KOH / g, 80 to 200 mg KOH / g, 80 to 150 mg KOH / g, 80 to 120 mg 120 KOH / g, 120 to 200 mg KOH / g, or 120 to 150 mg KOH / g. In certain embodiments, the TBN is in the range of 40 to 70 mg KOH / g.

[0040] In some embodiments, the lubricating oil composition of the present invention is suitable for use as a marine trunk piston engine oil (TPEO). The marine TPEO lubricant of the present disclosure is prepared according to SAE 30 or SAE 40 single grade specifications. Such marine TPEO lubricants have a TBN in the range of greater than 30 to 80 mg KOH / g (e.g., 35 to 75 mg KOH / g, 40 to 70 mg KOH / g).

[0041] In certain embodiments, the lubricating oil compositions of the present disclosure have a sulfated ash content of at least 1.50 wt % as determined by ASTM D 874. For example, the lubricating oil compositions of the present disclosure may have a sulfated ash level of 1.5 to 27 wt % as determined by ASTM D 874. By way of further example, the lubricating oil compositions of the present disclosure may have a sulfated ash content of 2.0 to 25.0 wt %, 2.5 to 25.0 wt %, 3.0 to 25.0 wt %, or 5.0 to 25.0 wt %, as determined by ASTM D 874.

[0042] Oil of lubricating viscosity

[0043] Based on the total weight of the composition, the lubricating oil composition of the present disclosure has at least 40 wt % of oil of lubricating viscosity, such as at least 50 wt % (e.g., at least 60 wt %, at least 70 wt %, at least 80 wt %, or at least 90 wt %). For example, the lubricating oil composition of the present disclosure may contain between 40 wt % and 95 wt %, between 50 wt % and 90 wt %, between 55 wt % and 85 wt % of oil of lubricating viscosity. Oil of lubricating viscosity may also be referred to as base oil.

[0044] According to certain embodiments of the present disclosure, the oil having a lubricating viscosity has a viscosity of 4.0 mm at 100°C. 2 / s to less than 8.5mm 2 / s kinematic viscosity. For example, an oil with lubricating viscosity may have a kinematic viscosity of 4.0 mm / s at 100°C. 2 / s to 8mm 2 / s, or 4.5mm 2 / s to 8mm 2 / s, or 5.0mm 2 / s to 7.5mm 2 / s kinematic viscosity.

[0045] The oil of lubricating viscosity of the present disclosure may contain only one base oil component or may contain a mixture of two or more base oil components to achieve the above kinematic viscosity. The oil of lubricating viscosity may be selected from any base oil of Class IV specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines (API 1509). Five base oil classes are summarized in Table 1:

[0046] Table 1

[0047]

[0048] (1) ASTM D2007

[0049] (2) ASTM D2270

[0050] (3) ASTM D3120, ASTM D4294 or ASTM D4297

[0051] Class I, Class II and Class III are mineral oil processing oils.Class IV base oil contains real synthetic molecular substances, which are produced by the polymerization of olefinically unsaturated hydrocarbons.Many Class V base oils are also real synthetic products, and can include diesters, polyol esters, polyalkylene glycols, alkylated aromatic compounds, polyphosphates, polyvinyl ethers and / or polyphenylene oxides etc., but can also be naturally occurring oils, such as vegetable oils.It should be noted that although Class III base oil is derived from mineral oil, the strict processing of these fluid experiences makes their physical properties very similar to some real synthetic substances, such as PAO.Therefore, the oil derived from Class III base oil can be called synthetic fluid in industry.

[0052] The base oil used in the disclosed lubricating oil composition can be mineral oil, animal oil, vegetable oil, synthetic oil or mixtures thereof. Suitable oils can be derived from hydrocracked, hydrogenated, hydrofined, unrefined, refined and re-refined oils and mixtures thereof.

[0053] Unrefined oils are those oils derived from natural, mineral or synthetic sources without or almost without further purification treatment. Refined oils are similar to unrefined oils, except that they have been processed in one or more purification steps, which can lead to improvements in one or more properties. Examples of suitable purification techniques are solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Refining to edible quality oils 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.

[0054] Re-refined oils are also known as reclaimed oils or reprocessed oils. These oils are obtained using the same or similar processes similar to refined oils. Typically, these oils are additionally processed by techniques involving the removal of spent additives and oil breakdown products.

[0055] Mineral oil can include oil obtained by drilling or oil obtained from plants and animals or any mixture thereof. Such oil can include castor oil, lard, olive oil, peanut oil, corn oil, soybean oil and linseed oil, and mineral lubricating oils, such as liquid petroleum and solvent-treated or acid-treated mineral lubricating oils of paraffin, cycloalkane or mixed paraffin-cycloalkane type. If desired, such oil may be partially or completely hydrogenated. Oil derived from coal or shale can also be useful.

[0056] Useful synthetic lubricating oils may include hydrocarbon oils such as polymerized, oligomeric or copolymerized olefins (e.g., polybutene, polypropylene, propylene / isobutylene copolymers); poly(1-hexene), poly(1-octene), trimers or oligomers of 1-decene, such as poly(1-decene), such materials are generally referred to as alpha-olefins, and mixtures thereof; alkylbenzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di-(2-ethylhexyl)-benzene); polyphenylenes (e.g., biphenyl, terphenyl, alkylated polyphenylenes); diphenyl alkanes, alkylated diphenyl alkanes, alkylated diphenyl ethers and alkylated diphenyl sulfides and their derivatives, analogs and homologs or mixtures thereof. Polyalphaolefins are typically hydrogenated materials.

[0057] Other synthetic lubricating oils include polyol esters, diesters, liquid esters containing phosphoric acid (e.g., tricresyl phosphate, trioctyl phosphate and diethyl ester of decanephosphonic acid) or polymerized tetrahydrofuran. Synthetic oils can be produced by Fischer-Tropsch reactions, and can typically be hydroisomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, oil can be prepared by Fischer-Tropsch gas-liquid synthesis procedures and other gas-liquid oils.

[0058] The base oil used for the formulated lubricating oil that can be used for the present disclosure is any one of the various oils corresponding to API Class I, Class II, Class III, Class IV and Class V oils and their mixtures. In one embodiment, the base oil is a blend of Class II base oil or two or more different base oils. In another embodiment, the base oil is a blend of Class I base oil or two or more different Class I base oils. Suitable Class I base oils include any light overhead fractions from a vacuum distillation tower, such as for example any light neutral, medium neutral and heavy neutral base oil stocks.

[0059] The base oil may also include residual base stocks or bottoms fractions, such as bright stock. Bright stock is a high viscosity base oil that is conventionally produced from residual stocks or bottoms and has been highly refined and dewaxed. The kinematic viscosity of bright stock at 40°C may be greater than 180 mm 2 / s (for example, greater than 250mm 2 / s, or even between 500 and 1100 mm 2 In certain embodiments, the lubricating oil composition does not contain bright stock.

[0060] Thickener

[0061] According to an embodiment of the present invention, in order to obtain a finished lubricating oil composition having a desired viscosity grade, a thickener may be added to the lubricating oil composition to increase its viscosity. It has been surprisingly found that replacing heavy neutral base oil and bright stock with a combination of a lighter neutral base stock and an olefin copolymer thickener in a marine lubricant provides a lubricating oil composition that exhibits improved resistance to deposit formation and oxidation stability in engines operating under high load conditions while achieving a suitable lubricating oil viscosity.

[0062] According to an embodiment of the present disclosure, a suitable thickener may include an olefin copolymer (OCP). On an active basis, such additives are typically present at 0.1% by weight or greater, such as 0.1 to 12% by weight, of the lubricating oil composition. In certain embodiments, the OCP is present at 0.2 to 10% by weight, 0.3 to 9% by weight, 0.4 to 8% by weight, or 0.5 to 7% by weight of the lubricating oil composition on an active basis. In a further embodiment, the OCP is present at 0.5 to 12.0% by weight, 0.5 to 5% by weight, or 1 to 2% by weight of the lubricating oil composition on an active basis. In a further embodiment, the OCP is present at 1.0% by weight or greater, such as 1.0 to 12.0% by weight, 1.0% to 5% by weight, 1.3% to 4.5% by weight, 1.5% to 4.0% by weight, 2.0 to 12.0% by weight, or 2.0% to 3.5% by weight of the lubricating oil composition on an active basis. In certain embodiments, the OCP is the only viscosity modifier or thickener present in the lubricating oil composition.

[0063] In certain embodiments, olefin copolymers are copolymers based on units of ethylene units and alpha olefins (e.g., normal alpha olefins, isomerized alpha olefins), such as ethylene-propylene copolymer compositions. Other alpha olefins suitable for replacing propylene or combining with ethylene and propylene to form terpolymers or tetrapolymers include, for example, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene; and branched alpha olefins, such as 4-methyl-1-pentene, 4-methyl-1-hexene, 4-methylpentene-1,4,4-dimethyl-1-pentene, 6-methylheptene-1, and mixtures thereof.

[0064] Olefin copolymers according to certain embodiments of the present invention advantageously have a number average molecular weight between 30,000 and 120,000 g / mol, preferably between 40,000 and 120,000 g / mol, more preferably between 45,000 and 115,000 g / mol. In some embodiments, such a molecular weight can balance useful thickening with the stability of the formulation under stress. The molecular weight combined with the above reference amount can provide a viscosity suitable for marine cylinders and TPEO lubricant compositions.

[0065] The shear stability index (SSI) of the olefin copolymer, i.e., its resistance to mechanical degradation under shear stress, is in the range of 5 to 50. In certain embodiments, the SSI is in the range of 15 to 50, such as 24 to 50, or 24 to 40.

[0066] The olefin copolymer according to certain embodiments of the present invention advantageously has an ethylene unit content in the range of 30 wt % to 80 wt %, preferably 30 wt % to 75 wt %, more preferably 49 wt % to 72 wt % relative to the weight of the olefin copolymer. The olefin copolymer according to the present invention also advantageously has an ethylene unit content in the range of 40 mol % to 90 mol %, preferably 40 mol % to 80 mol %, more preferably 50 mol % to 80 mol % relative to the mole number of the olefin copolymer.

[0067] The olefin copolymer according to certain embodiments of the present invention can be a bimodal ethylene copolymer composition having a first ethylene copolymer fraction with a relatively low ethylene content; and a second ethylene copolymer fraction with a relatively high ethylene content. In one embodiment, a polymerization process for producing an olefin copolymer may comprise copolymerizing two or more alpha olefin monomers (one of which is preferably ethylene; in some aspects, the other may be a C3-C 12 The olefin copolymers used in certain embodiments may include one or more of the olefin copolymers set forth in US20130203640, the disclosure of which is incorporated herein by reference in its entirety.

[0068] In certain embodiments of these embodiments, olefin copolymer compositions of the present disclosure may include (a) a first ethylene-α-olefin copolymer and (b) a second ethylene-α-olefin copolymer. As an example, the first ethylene-α-olefin copolymer (a) has an ethylene content of about 60 to about 80 weight %, and may be referred to herein as a "semi-crystalline" ethylene-α-olefin copolymer. More typically, the ethylene content of the first ethylene-α-olefin copolymer is about 63 to about 77 weight %, and even more typically, the ethylene content of the first ethylene-α-olefin copolymer is about 65 to about 75 weight %. The second ethylene-α-olefin copolymer (b) has an ethylene content of less than about 60 weight %, more typically less than about 55 weight % and even more typically about 42 to about 54 weight %, and is a ethylene-α-olefin copolymer less crystalline than the first ethylene-α-olefin copolymer (a), and may be referred to herein as an "amorphous" ethylene-α-olefin copolymer.

[0069] The melt flow rate ratio (MFRR) of the first ethylene-α-olefin copolymer (a) (defined as the ratio of the MFR measured at 230°C / 21.6kg and at 230°C / 2.16kg) can be >30, and more typically up to about 55, even more typically from about 33 to about 45, preferably >34, and more preferably from about 34 to about 45, and more preferably from about 35 to about 43. When the MFR condition is also observed, the MFR of the first ethylene-α-olefin copolymer (a) is at least about 1.5 g / 10min, and in another embodiment, the MFR is at least about 1.6 g / 10min. A more typical range of MFR is from about 1.5 g / 10min to about 6.5 g / 10min, and an even more typical range is from about 2.5 g / 10min to about 5.5 g / 10min. MFR is measured by ASTM D 1238 Condition L (230°C / 2.16kg). In one embodiment, the first ethylene-α-olefin copolymer (a) has a MFRR > 30 and a MFR of at least about 1.5 g / 10 min. More preferably, the first ethylene-α-olefin copolymer (a) has a MFRR > 34 and a MFR of at least about 1.6 g / 10 min.

[0070] In one embodiment, the olefin copolymer composition contains about 30% to about 70% by weight of the first ethylene-α-olefin copolymer (a) and about 70% to about 30% by weight of the second ethylene-α-olefin copolymer (b), based on the total amount of (a) and (b) in the composition. In another embodiment, the olefin copolymer composition contains about 40% to about 60% by weight of the first ethylene-α-olefin copolymer (a) and about 60% to about 40% by weight of the second ethylene-α-olefin copolymer (b), based on the total amount of (a) and (b) in the composition. In a specific embodiment, the olefin copolymer composition contains about 50 to about 54% by weight of the first ethylene-α-olefin copolymer (a) and about 46 to about 50% by weight of the second ethylene-α-olefin copolymer (b), based on the total amount of (a) and (b) in the composition.

[0071] In one embodiment, the weight average molecular weight of the first ethylene-α-olefin copolymer is from about 60,000 to about 120,000. In another embodiment, the weight average molecular weight of the first ethylene-α-olefin copolymer is from about 70,000 to about 110,000. In one embodiment, the weight average molecular weight of the second ethylene-α-olefin copolymer is from about 60,000 to about 120,000. In another embodiment, the weight average molecular weight of the second ethylene-α-olefin copolymer is from about 70,000 to about 110,000.

[0072] In one embodiment, the weight average molecular weight of the composition of the first ethylene-α-olefin copolymer and the second ethylene-α-olefin copolymer is from about 60,000 to about 120,000. In another embodiment, the weight average molecular weight of the composition of the first ethylene-α-olefin copolymer and the second ethylene-α-olefin copolymer is from about 70,000 to about 110,000. In a further embodiment, the weight average molecular weight of the composition of the first ethylene-α-olefin copolymer and the second ethylene-α-olefin copolymer is from about 80,000 to about 100,000. The molecular weight distribution of each ethylene-α-olefin copolymer may be less than about 2.5, and more typically from about 2.1 to about 2.4. The polymer distribution of each ethylene-α-olefin copolymer as determined by GPC is typically unimodal.

[0073] Other performance additives

[0074] The lubricating oil compositions of the present disclosure may contain one or more performance additives that can impart or improve any desired properties of the lubricating oil composition. Any additive known to those skilled in the art can be used in the lubricating oil compositions disclosed herein. Some suitable additives have been described by RM Mortier et al., "Chemistry and Technology of Lubricants", 3rd edition, Springer (2010) and LR Rudnik, "Lubricant Additives: Chemistry and Applications", 2nd edition, CRC Press (2009).

[0075] Generally, when used, the concentration of each additive in the lubricating oil composition may be in the range of 0.001 to 10 wt % (e.g., 0.01 to 5 wt % or 0.05 to 2.5 wt %) of the lubricating oil composition. Including diluent oil, each additive in the lubricating oil composition may be in the range of 0.5-45 wt % (e.g., 1.0 to 45 wt %, 5.0 to 40 wt %, 10 to 35 wt %, 20 to 32 wt %, or 25 to 30 wt %) of the lubricating oil composition. In addition, the total amount of additives in the lubricating oil composition may be in the range of 0.001 to 20 wt % (e.g., 0.01 to 15 wt % or 0.1 to 10 wt %) of the lubricating oil composition. Including the diluent oil, the total amount of additives in the lubricating oil composition can range from 0.5 to 78 wt % (e.g., 1.0 to 78 wt %, 5.0 to 78 wt %, 10 to 78 wt %, 20 to 78 wt %, 30 to 78 wt % or 45 to 78 wt %) of the lubricating oil composition.

[0076] By way of example, the lubricating oil composition of the present invention may contain one or more lubricating oil performance additives including detergents, dispersants, antiwear agents, antioxidants, friction modifiers, corrosion inhibitors, rust inhibitors, demulsifiers, foam inhibitors, viscosity modifiers, pour point depressants, nonionic surfactants, thickeners, etc. Some are discussed in more detail below.

[0077] Detergent

[0078] The lubricating oil composition of the present disclosure may include one or more detergents. Detergents are additives that reduce the formation of piston deposits (e.g., high temperature varnish and paint deposits in engines). Detergents generally have the property of neutralizing acids and are able to keep finely divided solids in suspension. Most detergents are metal salts of acidic organic compounds.

[0079] Metal-containing or ash-forming detergents can be used as both detergents to reduce or remove deposits and as acid neutralizers or rust inhibitors, thereby reducing wear and corrosion and extending engine life. Detergents typically include a polar head with a long hydrophobic tail. The polar head contains a metal salt of an acidic organic compound.

[0080] In the art, detergents are often referred to as neutral or overbased. Detergents containing substantially stoichiometric amounts of metal salts are often described as normal or neutral detergents. In embodiments where a large amount of a metal base is incorporated into the detergent by reacting an excess of a metal compound (e.g., an oxide or hydroxide) with an acidic gas (e.g., carbon dioxide), the detergent is referred to as overbased.

[0081] Overbased metal detergents are typically produced by carbonating (using CO2) a mixture of a hydrocarbon, a detergent acid (e.g., a sulfonic acid or carboxylate), a metal oxide or hydroxide (e.g., calcium oxide or calcium hydroxide), and a promoter such as xylene, methanol, and water. For example, to prepare overbased calcium sulfonate, calcium oxide or calcium hydroxide reacts with gaseous carbon dioxide to form calcium carbonate during the carbonation process. The sulfonic acid is neutralized with excess CaO or Ca(OH)2 to form a sulfonate.

[0082] Overbased detergents can be further characterized as low overbased, moderately overbased, or highly overbased. Low overbased detergents can be, for example, overbased salts having a TBN of less than 100. In one embodiment, the TBN of the low overbased salt can be from about 5 to about 80. In another embodiment, the TBN of the low overbased salt can be from about 10 to about 80. In yet another embodiment, the TBN of the low overbased salt can be from about 10 to about 50.

[0083] The moderately overbased detergent may be, for example, an overbased salt having a TBN of about 100 to about 250. In one embodiment, the moderately overbased salt may have a TBN of about 100 to about 200. In another embodiment, the moderately overbased salt may have a TBN of about 125 to about 175.

[0084] The overbased detergent may be, for example, an overbased salt having a TBN greater than 250. In one embodiment, the overbased salt may have a TBN of from about 250 to about 800.

[0085] Compounds useful in detergents include oil-soluble neutral and overbased sulfonates, phenates, sulfurized phenates, thiophosphonates, salicylates and naphthenates of metals, particularly alkali or alkaline earth metals such as barium, sodium, potassium, lithium, calcium and magnesium, and other oil-soluble carboxylates. The most commonly used metals are calcium and magnesium, and mixtures of calcium and / or magnesium with sodium, which may all be present in detergents used in lubricants.

[0086] In one embodiment, the detergent may be one or more alkali metal salts or alkaline earth metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid and is a carboxylate or salicylate. Suitable hydroxyaromatic compounds include mononuclear monohydroxy and polyhydroxy aromatic hydrocarbons having 1 to 4, preferably 1 to 3, hydroxyl groups.

[0087] Suitable hydroxyaromatic compounds include phenol, catechol, resorcinol, hydroquinone, pyrogallol, cresol, etc. In certain embodiments, the preferred hydroxyaromatic compound is phenol.

[0088] The alkyl substituted portion of the alkali metal salt or alkaline earth metal salt of the alkyl substituted hydroxyaromatic carboxylic acid can be derived from an alpha olefin having 10 to 80 carbon atoms. The olefin employed can be a linear, isomerized linear, branched or partially branched linear chain. The olefin can be a mixture of linear olefins, a mixture of isomerized linear olefins, a mixture of branched olefins, a mixture of partially branched linear olefins, or a mixture of any of the foregoing.

[0089] In some embodiments, the mixture of linear olefins is a mixture of normal alpha olefins selected from olefins having from 10 to 40 carbon atoms per molecule. In one embodiment, the normal alpha olefins are isomerized using at least one of a solid or liquid catalyst.

[0090] In some embodiments, at least about 75 mol % (e.g., at least about 80 mol %, at least about 85 mol %, at least about 90 mol %, at least about 95 mol %, or at least about 99 mol %) of the alkyl groups contained in the alkali metal salt or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid (such as the alkyl groups of the alkaline earth metal salt of an alkyl-substituted hydroxybenzoic acid detergent) are C 20In certain embodiments of these embodiments, the alkali metal salt or alkaline earth metal salt of the alkyl-substituted hydroxyaromatic carboxylic acid is an alkali metal salt or alkaline earth metal salt of an alkyl-substituted hydroxybenzoic acid derived from an alkyl-substituted hydroxybenzoic acid, wherein the alkyl group is an alkali metal salt or alkaline earth metal salt containing at least 75 mol% C 20 To C 28 In another embodiment, at least about 50 mol % (e.g., at least 60 mol %, at least 70 mol %, at least 80 mol %, at least 85 mol %, at least 90 mol %, at least 95 mol % or at least 99 mol %) of the alkyl groups of the alkali metal or alkaline earth metal salt of alkyl-substituted hydroxybenzoic acid are C 20 To C 24 Alkyl substituents.

[0091] In another embodiment, at least about 50 mol% (e.g., at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 85 mol%, at least 90 mol%, at least 95 mol%, or at least 99 mol%) of the alkyl groups of the alkali metal or alkaline earth metal salt of an alkyl-substituted hydroxybenzoic acid are C 14 To C 18 In another embodiment, the alkali metal or alkaline earth metal salt of the alkyl-substituted hydroxyaromatic carboxylic acid is derived from a C 10 -C 40 Normal alpha olefins, isomerized C 20 -C 28 Normal alpha olefins, or preferably isomerized C 20 -C 24 The alkyl groups of normal alpha olefins. In one embodiment, the alpha olefin isomerization level of the isomerized normal alpha olefin is between about 0.1 and about 0.4. In another embodiment, the alkyl groups are derived from at least two alkylphenols. The alkyl groups on at least one of the at least two alkylphenols are derived from isomerized alpha olefins. The alkyl groups on the second alkylphenol may be derived from branched or partially branched olefins, highly isomerized olefins, or mixtures thereof.

[0092] The alkyl-substituted portion of the alkali metal or alkaline earth metal salt of the alkyl-substituted hydroxyaromatic carboxylic acid can be derived from cashew nut shell liquid (CNSL) or hydrogenated distilled CNSL. Distilled CNSL is a mixture of biodegradable meta-hydrocarbyl-substituted phenols in which the hydrocarbyl groups are linear and unsaturated, including cardanol. Catalytic hydrogenation of distilled CNSL produces a mixture of meta-hydrocarbyl-substituted phenols that is primarily rich in 3-pentadecylphenol.

[0093] The alkali metal salt or alkaline earth metal salt of the alkyl-substituted hydroxyaromatic carboxylic acid can be a mixture of ortho and para isomers. In one embodiment, the alkyl-substituted hydroxyaromatic carboxylic acid can contain 1 to 99% of the ortho isomer and 99 to 1% of the para isomer. In another embodiment, the alkyl-substituted hydroxyaromatic carboxylic acid can contain about 5 to 70% of the ortho isomer and 95 to 30% of the para isomer.

[0094] The alkali metal or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid may be neutral or overbased. Typically, an overbased alkali metal or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid is one in which the TBN of the alkali metal or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid has been increased by methods such as the addition of an alkalinity source (e.g., lime) and an acidic overbased compound (e.g., carbon dioxide).

[0095] As noted, certain embodiments of lubricating oil formulations may use one or more sulfonate detergents, either alone or in combination with other detergents. Sulfonates can be prepared from sulfonic acids, which can be obtained by sulfonation of alkyl-substituted aromatic hydrocarbons (such as those obtained from petroleum fractionation) or by alkylation of aromatic hydrocarbons. Examples of alkyl-substituted aromatic hydrocarbons that can be sulfonated include those obtained by alkylating benzene, toluene, xylene, naphthalene, diphenyl or their halogen derivatives. Alkylation can be carried out in the presence of a catalyst using an alkylating agent having 3 to more than 70 carbon atoms. Alkaryl sulfonates typically contain 9 to 80 or more carbon atoms, preferably 16 to 60, preferably 16 to 30, and most preferably 20 to 24 carbon atoms per alkyl-substituted aromatic moiety.

[0096] The oil soluble sulfonates or alkylaryl sulfonic acids can be neutralized with metal oxides, hydroxides, alkoxides, carbonates, carboxylates, sulfides, hydrosulfides, nitrates, borates and ethers. The amount of metal compound is selected based on the desired TBN of the final product.

[0097] Metal salts of phenols and sulfurized phenols (e.g., phenates or sulfurized phenate detergents) are prepared by reaction of phenol or sulfurized phenol with a suitable metal compound such as an oxide or hydroxide. Sulfurized phenols can be prepared by reacting phenol with sulfur or a sulfur-containing compound such as hydrogen sulfide, a sulfur monohalide or a sulfur dihalide to form a product, which is typically a mixture of compounds in which two or more phenols are bridged by sulfur-containing bridges. Additional details on the general preparation of sulfurized phenates can be found, for example, in U.S. Pat. Nos. 2,680,096, 3,178,368, and 3,801,507, the contents of which are incorporated herein by reference.

[0098] The sulfur used to form the sulfurized compound may be in any allotropic form of sulfur.The sulfur may be present as molten sulfur or as a solid (eg, powder or granules) or as a suspension of the solid in a compatible hydrocarbon liquid.

[0099] In some embodiments, it is desirable to use calcium hydroxide as the calcium base because of its ease of handling relative to, for example, calcium oxide, and also because it provides superior results. Other calcium bases may also be used, such as calcium alkoxides.

[0100] Suitable alkylphenols that can be used are those in which the alkyl substituent contains a sufficient number of carbon atoms to render the resulting alkylphenol salt (e.g., overbased sulfurized calcium alkylphenol) composition oil soluble. Oil solubility may be provided by a single long chain alkyl substituent or by a combination of alkyl substituents. Typically, the alkylphenols used will be a mixture of different alkylphenols (e.g., C 20 To C 24 In one embodiment, suitable alkylphenols will be derived from an isomerized normal alpha olefin alkyl group having about 10 to about 40 carbon atoms per molecule, the isomerization level of the alpha olefin being about 0.1 to about 0.4. In one embodiment, the isomerized normal alpha olefin has about 20 to about 24 carbon atoms. In one embodiment, suitable alkylphenols will be derived from an alkyl group having a branched olefinic propylene oligomer or a mixture thereof having about 9 to about 80 carbon atoms. In one embodiment, the branched olefinic propylene oligomer or a mixture thereof has about 9 to about 40 carbon atoms. In one embodiment, the branched olefinic propylene oligomer or a mixture thereof has about 9 to about 18 carbon atoms. In one embodiment, the branched olefinic propylene oligomer or a mixture thereof has about 9 to about 12 carbon atoms.

[0101] In one embodiment, suitable alkylphenol compounds include distilled cashew nut shell liquid (CNSL) or hydrogenated distilled CNSL. Distilled CNSL is a biodegradable mixture of meta-hydrocarbyl-substituted phenols, wherein the hydrocarbyl groups are linear and unsaturated, including cardanol. Catalytic hydrogenation of distilled CNSL produces a mixture of meta-hydrocarbyl-substituted phenols that is primarily rich in 3-pentadecylphenol.

[0102] The alkylphenol may be p-alkylphenol, m-alkylphenol or o-alkylphenol. In certain embodiments, such as where an overbased product is desired, the alkylphenol is preferably predominantly p-alkylphenol, with no more than about 45 mole % of the alkylphenol being o-alkylphenol; and more preferably, no more than about 35 mole % of the alkylphenol being o-alkylphenol. Alkyl-hydroxytoluene or xylene may also be used, as well as other alkylphenols having one or more alkyl substituents in addition to at least one long-chain alkyl substituent. In the case of distilled cashew nut shell liquid, catalytic hydrogenation of distilled CNSL produces a mixture of meta-alkyl-substituted phenols.

[0103] In general, the selection of alkylphenols can be based on the properties desired for the marine diesel engine lubricating oil composition, particularly TBN and oil solubility.Additional information on the preparation of suitable alkylphenols can be found, for example, in U.S. Pat. Nos. 5,024,773, 5,320,763, 5,318,710 and 5,320,762, each of which is incorporated herein by reference.

[0104] Typically, the amount of detergent may be about 0.001 wt % to about 50 wt %, or about 0.05 wt % to about 25 wt %, or about 0.1 wt % to about 20 wt %, or about 0.01 to 15 wt %, based on the total weight of the marine diesel engine lubricating oil composition.

[0105] The detergents may also include "hybrid" or "composite" detergents formed with mixed surfactant systems including phenate and / or sulfonate components, such as phenate / salicylate, sulfonate / phenate, sulfonate / salicylate, sulfonate / phenate / salicylate, as described, for example, in U.S. Patents 6,429,178, 6,429,179, 6,153,565. The detergents may also include a methylene-bridged polyphenol composition prepared by the reaction of phenol with formaldehyde or a reversible polymer thereof, optionally sulfiding the methylene-bridged intermediate and subsequently reacting the intermediate with an excess of a metal base to produce a methylene-bridged polyphenol phenate composition. In one embodiment, the methylene-bridged polyphenol phenate composition may be further reacted with an epoxide. In one embodiment, the methylene-bridged polyphenol phenate composition is not sulfided.

[0106] Other detergents may be present in any suitable amount, such as from 0.1 to 45 wt %, or from 0.5 to 30 wt % of the lubricating oil composition.

[0107] Dispersants

[0108] The lubricating oil composition of the present disclosure may include one or more dispersants. During engine operation, oil-insoluble oxidation byproducts are produced. Dispersants help keep these byproducts in solution, thereby reducing their deposition on metal surfaces. Dispersants are generally referred to as ashless dispersants because they do not contain ash-forming metals before being mixed in the lubricating oil composition, and they generally do not produce any ash when added to the lubricant. Ashless dispersants are characterized by polar groups attached to hydrocarbon chains of relatively high molecular weight or weight. Typical ashless dispersants include N-substituted long chain alkenyl succinimides. Examples of N-substituted long chain alkenyl succinimides include polyisobutylene succinimides, the number average molecular weight of the polyisobutylene substituents of which is in the range of 500 to 5000 Daltons (e.g., 900 to 2500 Daltons). Succinimide dispersants and their preparation are disclosed, for example, in U.S. Patent Nos. 4,234,435 and 7,897,696. Succinimide dispersants are typically imides formed from polyamines, typically poly(ethylene amines).

[0109] In some embodiments, the lubricant composition includes at least one polyisobutylene succinimide dispersant derived from polyisobutylene having a number average molecular weight in the range of 500 to 5000 Daltons (e.g., 900 to 2500 Daltons). The polyisobutylene succinimide can be used alone or in combination with other dispersants.

[0110] The dispersant may also be post-treated by conventional methods by reaction with any of a variety of reagents. Among these reagents are boron compounds (e.g., boric acid) and cyclic carbonates (ethylene carbonate).

[0111] Another class of dispersants includes Mannich bases. Mannich bases are materials formed by the condensation of higher molecular weight alkyl-substituted phenols, polyalkylene polyamines, and aldehydes such as formaldehyde. Mannich bases are described in more detail in U.S. Pat. No. 3,634,515.

[0112] Another class of dispersants includes high molecular weight esters prepared by the reaction of a hydrocarbyl acylating agent and a polyhydroxy aliphatic alcohol such as glycerol, pentaerythritol or sorbitol. Such materials are described in more detail in U.S. Pat. No. 3,381,022.

[0113] Another class of dispersants includes the high molecular weight ester amides.

[0114] The dispersant may be present in an amount of 0.1 to 15 wt % of the lubricating oil composition.

[0115] Antiwear Agents

[0116] Antiwear agents reduce friction and excessive wear and are usually based on compounds containing sulfur or phosphorus or both. Of note are dihydrocarbyl dithiophosphate metal salts, where the metal can be an alkali or alkaline earth metal, or aluminum, lead, tin, molybdenum, manganese, nickel, copper or zinc. Zinc dihydrocarbyl dithiophosphate (ZDDP) is an oil-soluble salt of a dihydrocarbyl dithiophosphate and can be represented by the formula:

[0117] Zn[SP(S)(OR)(OR')]2

[0118] wherein R and R' may be the same or different hydrocarbon groups containing from 1 to 18 (e.g., 2 to 12) carbon atoms. To achieve oil solubility, the total number of carbon atoms (i.e., R and R') in the dithiophosphoric acid will generally be 5 or greater.

[0119] The antiwear agent may be present in an amount of 0.1 to 6 wt % of the lubricating oil composition.

[0120] Antioxidants

[0121] Antioxidants slow down the oxidative degradation of the base oil during use. This degradation can lead to deposits on metal surfaces, the presence of sludge or an increase in the viscosity of the lubricant.

[0122] Useful antioxidants include hindered phenols. Hindered phenol antioxidants typically contain sec-butyl and / or tert-butyl groups as sterically hindered groups. The phenol group may be further substituted with a hydrocarbon group (typically a straight or branched alkyl group) and / or a bridging group connected to a second aromatic group. Examples of hindered phenol antioxidants include 2,6-di-tert-butylphenol, 2,6-di-tert-butylcresol, 2,4,6-tri-tert-butylphenol, 2,6-di-alkyl-phenol propionate derivatives, and bisphenols such as 4,4′-bis(2,6-di-tert-butylphenol) and 4,4′-methylene-bis(2,6-di-tert-butylphenol).

[0123] Sulfurized alkylphenols and their alkali metal and alkaline earth metal salts may also be used as antioxidants.

[0124] Non-phenolic antioxidants that can be used include aromatic amine antioxidants such as diarylamines and alkylated diarylamines. Specific examples of aromatic amine antioxidants include N-phenyl-2-naphthylamine, 4,4'-dioctyldiphenylamine, butylated / octylated diphenylamine, nonylated diphenylamine, and octylated N-phenyl-2-naphthylamine.

[0125] The antioxidant may be present in an amount of 0.01 to 15.0 wt % of the lubricating oil composition.

[0126] Friction modifiers

[0127] Friction modifiers are any materials that can change the coefficient of friction of a surface lubricated by any lubricant or fluid containing such material. Suitable friction modifiers can include fatty amines, esters such as borated glycerides, fatty phosphites, fatty acid amides, fatty epoxides, borated fatty epoxides, alkoxylated fatty amines, borated alkoxylated fatty amines, metal salts of fatty acids, or fatty imidazolines, and condensation products of carboxylic acids and polyalkylene-polyamines. As used herein, the term "fat" associated with friction modifiers refers to a carbon chain having 10 to 22 carbon atoms, typically a straight carbon chain. Molybdenum compounds are also referred to as friction modifiers. Friction modifiers can be present in 0.01 to 10.0 weight % of the lubricating oil composition.

[0128] Rust inhibitor

[0129] Rust inhibitors generally protect lubricated metal surfaces from chemical attack by water or other contaminants. Suitable rust inhibitors may include suitable nonionic rust inhibitors, including nonionic polyoxyalkylene agents (e.g., polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate); 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 polyols; phosphate esters; (short chain) alkenyl succinic acid, partial esters thereof, and nitrogen-containing derivatives thereof; and synthetic alkyl aryl sulfonates (e.g., metal dinonyl naphthalene sulfonates). Such additives may be present in 0.01 to 5% by weight of the lubricating oil composition.

[0130] Demulsifier

[0131] Demulsifiers promote oil-water separation in lubricating oil compositions exposed to water or steam. Suitable demulsifiers include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof. Such additives may be present in an amount of 0.01 to 5% by weight of the lubricating oil composition.

[0132] Foam Inhibitor

[0133] Foam inhibitors delay the formation of stable foam. Siloxanes and organic polymers are typical foam inhibitors. For example, polysiloxanes, such as silicone oils or polydimethylsiloxanes, provide foam suppressing properties. Additional foam inhibitors include copolymers of ethyl acrylate and 2-ethylhexyl acrylate and optionally vinyl acetate. Such additives may be present in 0.001 to 1% by weight of the lubricating oil composition.

[0134] Viscosity Modifiers

[0135] Viscosity modifiers provide high and low temperature operability for lubricants. These additives impart shear stability at high temperatures and acceptable viscosity at low temperatures. Suitable viscosity modifiers may include polyolefins, olefin copolymers (OCPs), ethylene / propylene copolymers, polyisobutylenes, hydrogenated styrene-isoprene polymers, styrene / maleate copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkyl styrenes, and hydrogenated alkenyl aryl conjugated diene copolymers. Such additives may be present in 0.1 to 15 weight % of the lubricating oil composition.

[0136] Pour Point Depressants

[0137] Pour point depressants lower the lowest temperature at which a fluid will flow or be pourable. Examples of suitable pour point depressants include polymethacrylates, polyacrylates, polyacrylamides, condensation products of halogenated paraffins and aromatic compounds, carboxylic acid vinyl ester polymers, and terpolymers of dialkyl fumarates, vinyl esters of fatty acids and allyl vinyl ethers. Such additives may be present in 0.01 to 1.0 weight percent of the lubricating oil composition.

[0138] Nonionic surfactants

[0139] Nonionic surfactants such as alkylphenols can improve asphaltene handling during engine operation. Examples of such materials include alkylphenols having alkyl substituents from straight or branched chain alkyl groups having 9 to 30 carbon atoms. Other examples include alkylphenols, alkylnaphthols, and alkylphenol-aldehyde condensates where the aldehyde is formaldehyde such that the condensate is a methylene-bridged alkylphenol. Such additives may be present in 0.1 to 20 weight percent of the lubricating oil composition.

[0140] Markers

[0141] The lubricating oil composition of the present invention may contain a dye or marker component, such as a tracer, which is particularly useful for marking lubricants to protect brand assets, prevent misidentification and help identify leaks. The most useful types of markers or dyes are those that can be easily extracted, measured and / or identified from the marked liquid. Many additives and tracers that have been proposed for or are currently used to mark or label lubricants include color and fluorescent dyes (e.g., diazo dyes, anthraquinone dyes, phthalein dyes, etc.), radioactive materials, metal compounds or complexes (e.g., metal organic compounds, metal salts, metal oxides, metal coordination complexes, etc.), and various specific compounds that react with selected reagent combinations to provide intensely colored derivatives.

[0142] Examples of markers include materials selected from the group consisting of barium sulfate, bismuth trioxide, iodine, iodide, titanium oxide, zirconium oxide, gold, platinum, silver, tantalum, niobium, stainless steel, and combinations thereof. Materials such as certain metal soaps, metal soaps of fatty acids, metal carboxylates, or known metal driers may also be used as lubricant markers, the metal driers being supplied as solutions containing metals such as cobalt, lead, magnesium, titanium, zirconium, manganese, rhodium, platinum, aluminum, manganese, calcium, cerium, copper, nickel, vanadium, barium, tungsten, vanadium, and zinc, and mixtures thereof. Examples of zirconium-containing materials may include zirconium carboxylates such as zirconium 2-ethylhexanoate, zirconium octoate, and zirconium salicylate materials.

[0143] Use of lubricating oil composition

[0144] The lubricant composition can be effectively used as a lubricating oil for compression ignition internal combustion engines, including marine diesel engines, stationary gas engines, and the like.

[0145] The internal combustion engine may be a 2-stroke or a 4-stroke engine.

[0146] In an embodiment, the internal combustion engine is a marine diesel engine. The marine diesel engine can be a medium speed 4-stroke compression ignition engine with a speed of 250 to 1100 rpm or a low speed crosshead 2-stroke compression ignition engine with a speed of 200 rpm or less (e.g., 60 to 200 rpm).

[0147] Marine diesel engines can be lubricated with marine diesel cylinder lubricant (usually in 2-stroke engines), system oil (usually in 2-stroke engines) or crankcase lubricant (usually 4-stroke engines).

[0148] The term "marine" does not limit engines to those used in watercraft; as understood in the art, it also includes those used in other industrial applications, such as auxiliary power generation for main propulsion and stationary land-based engines for power generation.

[0149] In some embodiments, the internal combustion engine may be fueled with residual fuel, marine residual fuel, low sulfur marine residual fuel, marine distillate fuel, low sulfur marine distillate fuel, or high sulfur fuel.

[0150] Internal combustion engines may also be operated on "gaseous fuels," such as methane-based fuels (eg, natural gas), biogas, vaporized liquefied gas, or vaporized liquefied natural gas (LNG).

[0151] Example

[0152] The following illustrative examples are intended to be non-limiting.

[0153] The following components were used in the formulation of the marine lubricating oil compositions of the Examples. Generally, the marine lubricating oil compositions of the Examples included an oil of lubricating viscosity (base oil component), a thickener, and an additive package.

[0154] The base oil components used in the formulations of the examples include:

[0155] XOM 150N: ExxonMobil 150N Class I lubricating oil, kv at 100°C is 5.1mm 2 / s

[0156] XOM 600N: ExxonMobil 600N: Class I lubricant, kv 12.4mm at 100°C 2 / s

[0157] XOM 2500BS: ExxonMobil 2500BS: Class I lubricant, kv 30.6mm at 100°C 2 / s

[0158] RLOP 100R: Chevron 100R II type lubricant, kv 4.4mm at 100°C 2 / s

[0159] RLOP 220R: Chevron 220RLOP: Class II lubricant, kv 6.4mm at 100°C 2 / s

[0160] RLOP 600R: Chevron 600R RLOP: Class II lubricant, kv 12.0 mm at 100°C 2 / s

[0161] The olefin copolymer thickener used in the formulations of the examples is a concentrate of an olefin copolymer, particularly an ethylene-propylene copolymer, in a diluent. Therefore, in the tables listed below, the weight percentages of the OCP thickener listed are on an as is basis, not on an active basis. To obtain the weight percentage of the olefin copolymer on an active basis, the listed weight percentage of the OCP thickener should be multiplied by the weight percentage of the olefin copolymer present in the OCP thickener.

[0162] OCP-1: A concentrate having 6.30 wt% of a 50 SSI olefin copolymer in a Group II diluent oil and containing 60% ethylene and having a number average molecular weight (Mn) of 112,000 g / mol.

[0163] OCP-2: A concentrate having 10.00 wt% of 24 SSI olefin copolymer in a Group II diluent oil and containing 57% ethylene and having a number average molecular weight (Mn) of 40,000 g / mol.

[0164] OCP-3: A concentrate having 18.75 wt% 35 SSI olefin copolymer in a Group II diluent oil and containing 57% ethylene and having a number average molecular weight (Mn) of 49,000 g / mol.

[0165] OCP-4: A concentrate having 8.6 wt% of a 50 SSI olefin copolymer in a Group II diluent oil and containing 49% ethylene and having a number average molecular weight (Mn) of 84,000 g / mol.

[0166] The additive package used in the example formulations included:

[0167] Additive Package A: oil concentrate of high TBN calcium sulfonate detergent, oil concentrate of MOB sulfurized calcium phenate detergent, oil concentrate of LOB sulfurized calcium phenate detergent, oil concentrate of succinimide dispersant, tracer component and foam inhibitor.

[0168] Additive Package B: 7.5 wt% of 20 To C 24 410BN overbased calcium carboxylate detergent oil concentrate of isomerized alpha olefins (33.0 wt. % diluent oil), 5.2 wt. % derived from C 20 To C 24 An oil concentrate of 180 BN overbased calcium carboxylate detergent of isomerized normal alpha olefins (20 wt. % diluent oil), 0.7 wt. % secondary zinc dithiophosphate and 0.1 wt. % foam suppressor.

[0169] Additive Package C: 6.92 wt% 420BN calcium sulfonate detergent oil concentrate (38.7 wt% diluent oil), 6.0 wt% 17BN calcium sulfonate detergent oil concentrate (50.0 wt% diluent oil), 9.0 wt% derived from C 20 To C 24 An oil concentrate of 95BN sulfurized calcium phenate detergent of isomerized alpha olefins (20 wt% diluent oil), 0.2 wt% of an oil concentrate of a bis-succinimide dispersant derived from a 1000 MW PIB (32 wt% diluent oil), 1.5 wt% antioxidant, 0.11 wt% foam inhibitor and diluent oil.

[0170] Additive Package D: 5.0 wt% of 20 To C 24260BN sulfurized calcium phenate detergent oil concentrate of isomerized alpha olefins (40 wt% diluent oil), 4.0 wt% derived from C 20 To C 24 410BN overbased calcium carboxylate detergent oil concentrate of isomerized alpha olefins (33.0 wt. % diluent oil), 5.45 wt. % derived from C 20 To C 24 An oil concentrate of 180 BN overbased calcium carboxylate detergent of isomerized normal alpha olefins (20 wt% diluent oil), 0.2 wt% of an oil concentrate of a bis-succinimide dispersant derived from a 1000 MW PIB (32 wt% diluent oil), 1.5 wt% antioxidant, 0.11 wt% foam inhibitor and diluent oil.

[0171] The following examples were evaluated for their degree of high temperature detergency and oxidative stability using the following tests. The results for each example are listed in Tables 2-5.

[0172] Test Method

[0173] Micro coker

[0174] This method is used to evaluate the high temperature deposit / varnish forming tendency of land and marine lubricants. A defined amount of test oil is placed in a shallow groove of an inclined aluminum panel. A temperature gradient is applied to the panel and the test oil is evenly distributed in the shallow groove. The panel is heated and the temperature at which deposit / varnish formation begins is determined by the appearance of the panel at the end of the test.

[0175] DSC oxidation test

[0176] According to ASTM D-6186, the DSC test is used to evaluate the thin film oxidation stability of the test oil. During the test, the heat flow into and out of the test oil in the sample cup is compared to the reference cup. The oxidation onset temperature is the temperature at which the test oil begins to oxidize. The oxidation induction time is the time when the test oil begins to oxidize. A longer oxidation induction time means better performance. The oxidation reaction is exothermic and is clearly shown by the heat flow. The oxidation induction time is calculated to evaluate the thin film oxidation stability of the test oil.

[0177] Improved Petroleum Institute 48 (MIP-48) Test

[0178] The MIP-48 test consists of a hot portion and an oxidation portion. During both portions of the test, the test samples are heated. In the hot portion of the test, nitrogen is passed through the heated oil sample for 24 hours, and in parallel, during the oxidation portion of the test, air is passed through the heated oil sample for 24 hours. The samples are cooled, and the viscosities of both samples are determined. The viscosity increase of the test oil caused by oxidation is determined and corrected for thermal effects. The oxidation-based viscosity increase of each marine lubricant composition is calculated by subtracting the kinematic viscosity of the nitrogen blown sample at 200°C from the kinematic viscosity of the blown sample at 200°C, and dividing the subtraction product by the kinematic viscosity of the nitrogen blown sample at 200°C. This is done to correct for potential evaporation effects or any other thermal effects during the test, thereby focusing on the impact of oxidation. This correction may result in negative values. Test oils that exhibit better stability to oxidation-based viscosity increase will result in lower % absolute values.

[0179] result

[0180] Examples 1-4 and Comparative Example A

[0181] Examples 1-4 and Comparative Example A were formulated to 70BN, SAE 50 viscosity grade (kv 19.5 mm at 100°C) using 20.0 wt.% of Additive Package A. 2 / s) marine cylinder lubricating oil composition. Comparative Example A was formulated using a more conventional combination of heavy neutral oil RLOP 600R and XOM 2500BS bright stock to achieve appropriate lubricating oil viscosity. Examples 1-4 each contain a combination of light neutral oil RLOP 100R and olefin copolymer thickener to achieve appropriate lubricating oil viscosity for the finished lubricant. The weight percentages of OCP thickener listed are on an as is basis. The high temperature detergency and oxidation performance of each lubricant were evaluated using a microcoker and DSC oxidation test, respectively. The results for each sample are listed in Table 2 below.

[0182] Table 2

[0183]

[0184] The results listed in Table 2 show that the marine cylinder lubricating oil composition containing the combination of the light neutral oil RLOP 100R and the olefin copolymer thickener exhibits surprisingly superior detergency and oxidation performance over Comparative Example A. The improved performance of the inventive examples is demonstrated by higher lacquer formation temperatures and higher oxidation induction times compared to the comparative examples. Additionally, Examples 1-4 were formulated to achieve an SAE 50 viscosity grade without the use of a heavy neutral oil and without the use of bright stock in the finished lubricating oil composition.

[0185] Example 5 and Comparative Example B

[0186] Example 5 and Comparative Example B were formulated to contain 13.5 wt% of Additive Package B as a 40BN, SAE 40 viscosity grade (kv 14.0 mm at 100°C). 2 / s) marine trunk piston engine lubricating oil composition. Comparative Example B was formulated using a more conventional combination of heavy neutral oil 600R and XOM 2500BS bright stock to achieve appropriate lubricating oil viscosity. Example 5 contains a combination of light neutral oil 220R and olefin copolymer thickener to achieve appropriate lubricating oil viscosity for the finished lubricant. The weight percentages of OCP thickener listed are on an as is basis. The oxidative stability of each lubricant was evaluated using a DSC oxidation test. The results for each sample are listed in Table 3 below.

[0187] Table 3

[0188]

[0189] The results in Table 3 show that the marine trunk piston engine lubricating oil composition containing the combination of light neutral oil 220R and olefin copolymer thickener exhibits surprisingly better oxidation performance than Comparative Example B. The improved performance is evidenced by the higher oxidation induction time of Example 5 when compared to Comparative Example B. Additionally, Example 5 was formulated to achieve an SAE 40 viscosity grade without the use of heavy neutral oil and bright stock in the finished lubricating oil composition.

[0190] Example 6 and Comparative Example C

[0191] Example 6 and Comparative Example C were formulated as 40BN, SAE 50 viscosity grade (kv 18.5 mm at 100°C) containing 24.98 wt% of Additive Package C. 2 / s) marine cylinder lubricant composition. Comparative Example C was formulated using a more conventional combination of heavy neutral oil 600R and XOM2500BS bright stock to achieve the appropriate lubricant viscosity. Example 6 contained a combination of light neutral oil 220R and olefin copolymer thickener to achieve the appropriate lubricant viscosity for the finished lubricant. The weight percentages of OCP thickener listed are on an as is basis. The oxidative stability of each lubricant was evaluated using a DSC oxidation test. The results for each sample are listed in Table 4 below.

[0192] Table 4

[0193]

[0194] The results in Table 4 show that the marine cylinder lubricating oil composition containing the combination of light neutral oil 220R and olefin copolymer thickener exhibits surprisingly better oxidation performance than Comparative Example C. The improved performance is evidenced by the higher oxidation induction time of Example 6 when compared to Comparative Example C. Additionally, Example 6 was formulated to achieve an SAE 50 viscosity grade without the use of heavy neutral oil and bright stock in the finished lubricating oil composition.

[0195] Example 7 and Comparative Example D

[0196] Example 7 and Comparative Example D were formulated as 40BN, SAE 50 viscosity grade (kv 18.5 mm at 100°C) containing 17.12 wt% of Additive Package D. 2 / s) marine cylinder lubricant composition. Comparative Example D was formulated using a more conventional combination of heavy neutral oil 600R and XOM2500BS bright stock to achieve the appropriate lubricant viscosity. Example 7 contains a combination of light neutral oil 220R and olefin copolymer thickener to achieve the appropriate lubricant viscosity for the finished lubricant. The weight percentages of OCP thickener listed are on an as is basis. The oxidative stability of each lubricant was evaluated using a DSC oxidation test. The results for each sample are listed in Table 5 below.

[0197] Table 5

[0198]

[0199] The results in Table 5 show that the marine cylinder lubricating oil composition containing the combination of light neutral oil 220R and olefin copolymer thickener exhibits surprisingly better oxidation performance than Comparative Example D. The improved performance is demonstrated by the higher oxidation induction time of Example 7 when compared to Comparative Example D. Additionally, Example 7 was formulated to achieve an SAE 50 viscosity grade without the use of heavy neutral oil and bright stock in the finished lubricating oil composition.

[0200] The above specific embodiments have been shown by way of example, and it should be understood that these embodiments are susceptible to various modifications and alternative forms, and can also be used in any appropriate combination. It should also be understood that the claims are not intended to be limited to the specific forms disclosed, but to cover all modifications, equivalent forms, and alternative forms that fall within the spirit and scope of the present disclosure.

Claims

1. A marine diesel engine lubricating oil composition, comprising: (a) at least 40% by weight of an oil of lubricating viscosity having a viscosity of 4.0 to less than 8.5 mm at 100°C 2 / s kinematic viscosity; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000; and wherein the marine diesel engine lubricating oil composition has a TBN greater than 30 mg KOH / g, and further wherein the marine diesel engine lubricating oil composition is a monograde lubricating oil composition that meets the requirements of the SAE J300 specification revised in January 2015 for SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oils.

2. The composition according to claim 1, wherein the one or more olefin copolymers are bimodal and have a content of ethylene units ranging from 30% to 80% by weight relative to the weight of the olefin copolymer.

3. The composition of claim 1, wherein the one or more olefin copolymers are present in an amount of 0.5 to 5 weight percent of the lubricating oil composition on an active basis.

4. The composition of claim 1, wherein the one or more olefin copolymers are present at 1 to 2 weight percent of the lubricating oil composition on an active basis.

5. The composition of claim 1 wherein the one or more olefin copolymers are the only viscosity modifiers present in the lubricating oil composition.

6. The composition of claim 1, wherein the lubricating oil composition is free of bright stock.

7. The composition of claim 1, wherein the lubricating oil composition has a sulfated ash content of 1.5 wt% or greater.

8. The composition of claim 1, wherein the lubricating oil composition is a marine cylinder lubricating oil having a TBN of greater than 30 to 200 mg KOH / g.

9. The composition of claim 1, wherein the lubricating oil composition is a marine trunk piston engine oil having a TBN of greater than 30 to 80 mg KOH / g.

10. A method of thickening a lubricating oil composition in a marine diesel internal combustion engine, the method comprising adding to the engine a lubricating oil composition comprising: (a) at least 40% by weight of an oil of lubricating viscosity having a kinematic viscosity at 100° C. of 4.0 to less than 8.5 mm 2 / s; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000; and wherein the marine diesel lubricating oil composition has a TBN greater than 30 mg KOH / g, and further wherein the marine diesel lubricating oil composition is a monograde lubricating oil composition that meets the requirements of the SAE J300 specification revised in January 2015 for SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oils.

11. The method of claim 10, wherein the one or more olefin copolymers are present at 1 to 2 weight percent of the lubricating oil composition on an active basis.

12. The method of claim 10, wherein the one or more olefin copolymers are the only viscosity modifiers present in the lubricating oil composition.

13. The method of claim 10, wherein the lubricating oil composition is free of bright stock.

14. The method of claim 10, wherein the lubricating oil composition has a sulfated ash content of 1.5 wt% or greater.

15. The method of claim 10, wherein the lubricating oil composition is a marine cylinder lubricating oil having a TBN of greater than 30 to 200 mg KOH / g.

16. The method of claim 10, wherein the lubricating oil composition is a marine trunk piston engine oil having a TBN of greater than 30 to 80 mg KOH / g.

17. A method of controlling deposit formation in an internal combustion engine, the method comprising operating the internal combustion engine with a lubricating oil composition comprising: (a) at least 40% by weight of an oil of lubricating viscosity having a kinematic viscosity at 100° C. of 4.0 to less than 8.5 mm 2 / s; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000; and wherein the marine diesel lubricating oil composition has a TBN greater than 30 mg KOH / g, and further wherein the marine diesel lubricating oil composition is a monograde lubricating oil composition that meets the requirements of the SAE J300 specification revised in January 2015 for SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oils.

18. The method of claim 17, wherein the one or more olefin copolymers are present at 1 to 2 weight percent of the lubricating oil composition on an active basis.

19. The method of claim 17, wherein the one or more olefin copolymers are the only viscosity modifiers present in the lubricating oil composition.

20. The method of claim 17, wherein the lubricating oil composition is free of bright stock.

21. The method of claim 17, wherein the lubricating oil composition has a sulfated ash content of 1.5 wt% or greater.

22. The method of claim 17, wherein the lubricating oil composition is a marine cylinder lubricating oil having a TBN of greater than 30 to 200 mg KOH / g.

23. The method of claim 17, wherein the lubricating oil composition is a marine trunk piston engine oil having a TBN of greater than 30 to 80 mg KOH / g.

24. A marine diesel engine lubricating oil composition, comprising: (a) at least 40% by weight of an oil of lubricating viscosity having a viscosity of 4.0 to less than 8.5 mm at 100°C 2 / s kinematic viscosity; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000, wherein the one or more olefin copolymers are present at 1.0 wt. % or more of the lubricating oil composition on an active basis; and The marine diesel engine lubricating oil composition is a monograde lubricating oil composition that meets the requirements of the SAE J300 specification revised in January 2015 for SAE30, SAE 40, SAE 50 or SAE 60 monograde lubricating oils.

25. The lubricating oil composition of claim 24, wherein the one or more olefin copolymers are present at 1.0 wt% to 5 wt% of the lubricating oil composition on an active basis.

26. The lubricating oil composition of claim 24, wherein the lubricating oil composition is free of bright stock.

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