Diesel engine lubricating oil composition for ships

Abstract

The marine diesel engine lubricating oil composition contains (a) at least 40 wt.% of an oil having a lubricating viscosity with 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 lubricating oil composition has a TBN exceeding 30 mg KOH / g. The marine diesel lubricating oil composition is a monograde lubricating oil composition that meets the specifications of SAE J300 requirements revised in January 2015 for SAE30, SAE40, SAE50, or SAE60 monograde lubricating oils.

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 below and / or claimed. This discussion is believed to be useful in providing background information to the reader to facilitate a better understanding of various aspects of the present disclosure. Accordingly, these descriptions should be read in this context and should not be construed as an admission of prior art.

[0003] Marine diesel internal combustion engines can generally be classified as low-speed, medium-speed, or high-speed engines. Low-speed diesel engines are unique in terms of size and operating method. These engines are very large and typically operate in the range of about 60 to 200 revolutions per minute (rpm). Low-speed diesel engines operate on a two-stroke cycle and are typically direct-coupled and self-reversing engines with a "crosshead" structure that separates the power cylinder from the crankcase with a diaphragm to prevent combustion products from entering the crankcase and mixing with the crankcase oil, and one or more stuffing boxes. Marine two-stroke diesel cylinder lubricants need to meet performance requirements in order to cope with the severe operating conditions required by the latest larger-bore engines driven in a state where the output, load, and temperature of the cylinder liner vary greatly. Since the combustion zone is completely separated from the crankcase, those skilled in the art have come to lubricate the combustion chamber and the crankcase with different lubricating oils called cylinder lubricants and system oils, respectively. Marine cylinder lubricants and system oils are subject to their own requirements.

[0004] In a two-stroke crosshead engine, cylinder oil is injected separately into each cylinder by a lubricating device arranged around the cylinder liner, and the cylinders are lubricated by the total loss system. The cylinder lubricant is not recycled and burns with the fuel. The cylinder lubricant must provide a strong film between the cylinder liner and the piston rings to sufficiently lubricate the cylinder walls and prevent scuffing, 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 cylinder lubricants, system oils are not exposed to the combustion chambers where the fuel is burned and are formulated to last as long as possible to maximize the oil life.

[0005] Medium-speed engines typically operate in the range of about 250 to 1100 rpm and operate on a four-stroke cycle. These engines are typically of the trunk piston design. In a trunk piston engine, unlike a crosshead engine, a single lubricating oil is used for lubrication in all areas of the engine. Therefore, trunk piston engine oils have their own requirements. The main lubricating oil performance parameters for operating a trunk piston engine include deposit control in the piston cooling galleries and piston ring packs, oxidation and viscosity increase control, demulsibility performance, and sludge control. In the case of operation with marine residual fuel, these performance parameters are affected almost solely by asphaltene contamination from the marine residual fuel.

[0006] Due to recent health and environmental concerns, regulations have been introduced that mandate the use of low-sulfur fuels in the operation of marine diesel engines. As a result, manufacturers are now generally designing marine diesel engines for use with a variety of fuels, including non-residual gas fuels (e.g., compressed or liquefied natural gas), high-quality distillate fuels, in contrast to lower-quality middle or heavy fuels such as marine residual fuels that generally have a higher sulfur content and a higher asphaltene content. In the case of operation with non-residual fuels, the fuels contain no significant asphaltenes present in the fuel, and the sulfur levels are much lower. When lower-sulfur fuels burn, less acid is formed in the combustion chamber.

[0007] One of the main features by which lubricants serve to protect marine diesel engines is the "thickness", i.e., the viscosity, of the lubricating oil film. Lubricants for lubricating marine diesel internal combustion engines have high viscosity requirements in the industry because of the low operating speed and high load, and are typically high-viscosity monograde (i.e., those showing little or no viscosity index improvement characteristics) lubricants of SAE30, SAE40, SAE50, or SAE60 viscosity grades. Since hydrocracking results in viscosity loss of the base stock, marine oils generally cannot be formulated with hydrocracked base stock alone. To achieve an appropriate lubricating oil film thickness, conventional marine formulations typically include a majority amount of heavy neutral oil and / or high-viscosity bright stock in marine lubricants, and bright stock is a highly refined and dewaxed high-viscosity base oil produced from residual stock or bottoms.

[0008] However, due to the presence of oxidatively unstable aromatics, it is not always desirable to rely on bright stock. Furthermore, the availability of bright stock is decreasing, and as a result, alternative solutions are needed to impart the desired viscosity to lubricants for high-volume applications such as marine engines. With the increasing severity of design changes in modern marine engines and changes in regulations regarding fuel quality, along with the reduction in bright stock capacity, there is a continuing need for improved marine diesel lubricant formulation technology to achieve the required high viscosity in marine lubricants while improving performance.

Summary of the Invention

[0009] The following describes an overview of certain embodiments disclosed herein. It should be understood that these aspects are presented merely to provide the reader with a brief overview of these particular embodiments and are not intended to limit the scope of the present disclosure. In fact, the present disclosure may encompass various aspects not described below.

[0010] Generally, in one aspect, the present disclosure relates to a marine diesel lubricant composition comprising: (a) at least 40 wt.% of an oil having a lubricating viscosity with a kinematic viscosity at 100 °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 lubricant composition has a TBN exceeding 30 mg KOH / g and is a monograde lubricant composition that meets the specifications of the January 2015 revision of SAE J300 for SAE 30, SAE 40, SAE 50, or SAE 60 monograde lubricants.

[0011] In another aspect, the present disclosure relates to a method of thickening a lubricant composition for a marine diesel internal combustion engine. The method comprises adding to the engine: (a) 100 oAn oil having a lubricating viscosity with a kinematic viscosity at 100 °C of less than 4.0 to 8.5 mm2 / s and at least 40 wt.%; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000, and adding a lubricating oil composition containing the same. The marine diesel lubricating oil composition has a TBN exceeding 30 mgKOH / g and is a monograde lubricating oil composition that meets the specifications of the SAE J300 requirements revised in January 2015 for SAE30, SAE40, SAE50, or SAE60 monograde lubricating oils.

[0012] In a further aspect, the present disclosure relates to a method of controlling deposit formation in an internal combustion engine. The method includes operating an internal combustion engine using a lubricating oil composition. The lubricating oil composition includes (a) an oil having a lubricating viscosity with a kinematic viscosity at 100 °C of less than 4.0 to 8.5 mm2 / s and at least 40 wt.%; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000. The marine diesel lubricating oil composition has a TBN exceeding 30 mgKOH / g and is a monograde lubricating oil composition that meets the specifications of the SAE J300 requirements revised in January 2015 for SAE30, SAE40, SAE50, or SAE60 monograde lubricating oils.

Mode for Carrying Out the Invention

[0013] Definition As used herein, the following words and expressions have the meanings set forth below when used.

[0014] "Major amount" means more than 40 wt.% of the composition.

[0015] "Minor amount" means less than 40 wt.% of the composition.

[0016] "Residual fuel for ships" refers to a combustible material in large ship engines where the carbon residue is at least 2.5 wt.% (e.g., at least 5 wt.%, or at least 8 wt.%) (with respect to the total weight of the fuel) and the viscosity at 50 °C exceeds 14.0 cSt. By way of example, it is a residual fuel for ships as defined in the International Organization for Standardization (ISO) standard ISO 8217:2005 "Petroleum products - Fuels (class F) - Specifications of marine fuels", the content of which is hereby incorporated by reference in its entirety.

[0017] "Residual fuel" refers to a fuel that meets the specifications of residual marine fuels as defined in the ISO 8217:2010 international standard. "Low-sulfur marine fuel" refers to a fuel that meets the specifications of residual marine fuels as defined in the ISO 8217:2010 standard and, in addition, the sulfur content is about 1.5 wt.% or less, or about 0.5 wt.% or less, with respect to the total weight of the fuel.

[0018] "Distillate fuel" refers to a fuel that meets the specifications of distillate marine fuels as defined in the ISO 8217:2010 international standard. "Low-sulfur distillate fuel" refers to a fuel that meets the specifications of distillate marine fuels as defined in the ISO 8217:2010 international standard and, in addition, the sulfur content is about 0.1 wt.% or less, or even about 0.005 wt.% or less, with respect to the total weight of the fuel.

[0019] "Low-sulfur fuel" refers to a fuel where the sulfur content is 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, with respect to the total weight of the fuel.

[0020] "High-sulfur fuel" is a fuel where the sulfur content exceeds 1.5 wt.% with respect to the total weight of the fuel.

[0021] The term "on an active substance basis" refers to an additive material that is not a diluent oil or solvent.

[0022] As used herein and in the claims, "alpha-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 "alpha-olefin" includes linear and branched alpha-olefins unless otherwise specified. In the case of branched alpha-olefins, the branch can be at the 2-position (vinylidene) and / or at the 3-position or higher relative to the olefin double bond. Whenever used herein and in the claims, the term "vinylidene" refers to an alpha-olefin having a branch at the 2-position relative to the olefin double bond. Alpha-olefins are almost always mixtures of isomers and often mixtures of compounds having different numbers of carbon atoms. Low molecular weight alpha-olefins, for example, C6, C8, C 10 , C 12 and C 14 alpha-olefins are almost exclusively 1-olefins. In high molecular weight olefin cuts such as C 16 -C 18 or C 20 -C 24 etc., the proportion of double bonds isomerized to the internal or vinylidene position is increasing.

[0023] "Normal alpha-olefin" (NAO) refers to a linear aliphatic monoolefin having a carbon-carbon double bond between the first and second carbon atoms. Note that "normal alpha-olefin" is not synonymous with "linear alpha-olefin" because the term "linear alpha-olefin" may include linear olefin compounds having a double bond between the first and second carbon atoms.

[0024] "Isomerized olefin" or "isomerized normal alpha-olefin" refers to an olefin obtained by isomerizing an olefin. In general, isomerized olefins have double bonds at positions different from those of the starting olefins from which they are derived and may have different characteristics.

[0025] "Isomerization level (I)" refers to the isomerization level measured by NMR method. The isomerization level of olefins was determined by hydrogen-1 (1H) NMR. The NMR spectrum was obtained at 400 MHz in chloroform-d1 on a Bruker Ultrashield Plus 400 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) bonded to methylene backbone groups (-CH2-) (chemical shift 1.01 - 1.38 ppm), and is defined by the equation (I) = m / (m + n), where m is the NMR integration for methyl groups with chemical shifts between 0.30 ± 0.03 and 1.01 ± 0.03 ppm, and n is the NMR integration for methylene groups with chemical shifts between 1.01 ± 0.03 and 1.38 ± 0.10 ppm.

[0026] The terms "total base number" or "TBN" or "BN" refer to the level of alkalinity in an oil sample, which indicates the ability of the composition to continue to neutralize corrosive acids according to ASTM standard number D2896 or equivalent procedures. In the test, the change in electrical conductivity is measured, and the results are expressed in mg KOH / g (milligram equivalents of KOH required to neutralize 1 gram of the product). Thus, a high TBN indicates that the product is strongly basic and, as a result, has a greater reserve of base for neutralizing acids. It should be understood that when TBN values are introduced in this specification, they are expressed in units of mg KOH / g.

[0027] "Overbased" is used to describe a metal detergent in which the ratio of the number of equivalents of the metal part to the number of equivalents of the acid part is greater than 1.

[0028] "Soap" means a neutral detergent compound containing a stoichiometric amount of metal to achieve the neutralization of one or more acidic groups present in the organic acids used in the manufacture of detergents.

[0029] "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 can be selected from the group consisting of calcium, barium, magnesium and strontium. Calcium and magnesium are preferred.

[0030] "Weight percent" (wt.%) means, unless otherwise specified, the percentage by which the listed component(s), compound(s) or substituent(s) represent of the total weight of the composition as a whole. All percentages reported are weight percentages based on the active ingredient basis (i.e., regardless of carrier or diluent oil) unless otherwise stated. The diluent oil for 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 a mixture thereof). The weight percentage representing the combination of the component and the carrier or diluent oil is called the "as-received" weight percentage.

[0031] The term "sulfated ash content" refers to the amount of metal-containing additives (e.g., calcium, magnesium, molybdenum, zinc) in the lubricating oil composition and is typically measured in accordance with ASTM D874, which is incorporated herein by reference.

[0032] Lubricating oil composition Surprisingly, in marine lubricants, replacing heavy neutral base oil and bright stock with a combination of a lighter neutral base oil and an olefin copolymer thickener (e.g., completely replacing) provides a lubricating oil composition with improved resistance to deposit formation and oxidation stability in engines operating under various load conditions such as high load conditions while achieving an appropriate lubricating oil viscosity.

[0033] 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 having a kinematic viscosity at 100 °C of 4.0 mm 2 / s 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; wherein the lubricating oil composition is a monograde lubricating oil composition that meets the specifications of SAE J300 revised in January 2015 for 30, 40, 50, or 60 monograde engine oils and has a TBN of more 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.

[0034] The lubricating oil composition may be a monograde lubricating oil composition that meets the specifications of the January 2015 revised SAE J300 requirements for 30, 40, 50, or 60 monograde engine oils. SAE 30 oil has a kinematic viscosity at 100 °C of 9.3 to <12.5 mm 2 / s. SAE 40 oil has a kinematic viscosity at 100 °C of 12.5 to <16.3 mm 2 / s. SAE 50 oil has a kinematic viscosity at 100 °C of 16.3 to <21.9 mm 2 / s. SAE 60 oil has a kinematic viscosity at 100 °C of 21.9 to <26.1 mm 2 / s.

[0035] 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 to meet the SAE 30, SAE 40, SAE 50, or SAE 60 monograde specifications and provides a sufficiently thick lubricant film on the cylinder liner wall at high temperatures.

[0036] In addition to providing a sufficient degree of lubricity, one of the main functions of a cylinder lubricant for ships is to neutralize the sulfur-based acidic components of the burned sulfur-containing fuel. This neutralization is typically achieved by including basic species such as overbased metal detergents. The neutralization ability of the oil is characterized by its base number and is measured by its total base number (TBN). Typically, for sulfur-containing fuels used in marine diesel engines, there is a need for a marine cylinder lubricant with high detergency and neutralization ability even when the oil is exposed to heat and other stresses for a short time.

[0037] To enable sufficient neutralization and cleaning action, the marine diesel cylinder lubricant of the present disclosure has a TBN of at least 30 mg KOH / g. By way of example, the TBN can range from 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, or greater than 30 to 100 mg KOH / g, or greater than 30 to 80 mg KOH / g, or 60 to 200 mg KOH / g, or 60 to 150 mg KOH / g, or 60 to 120 mg KOH / g, or 60 to 100 mg KOH / g, or 60 to 80 mg KOH / g, or 80 to 200 mg KOH / g, or 80 to 150 mg KOH / g, or 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 ranges from 40 to 70 mg KOH / g.

[0038] In some embodiments, the lubricating oil composition of the present invention is suitable for use as a trunk piston engine oil (TPEO) for ships. The marine TPEO lubricant of the present disclosure is manufactured to meet the SAE30 or SAE40 monograde specifications. The marine TPEO lubricant has a TBN in the range of greater than 30 mg KOH / g to 80 mg KOH / g (e.g., 35 to 75 mg KOH / g, 40 to 70 mg KOH / g).

[0039] In certain embodiments, the lubricating oil composition of the present disclosure has a sulfuric acid ash content of at least 1.50 wt.% as determined by ASTM D874. For example, the lubricating oil composition of the present disclosure may have a sulfuric acid ash level of 1.5 to 27 wt.% as determined by ASTM D874. As a further example, the lubricating oil composition of the present disclosure may have a sulfuric acid 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 D874.

[0040] Oil of lubricating viscosity The lubricating oil composition of the present disclosure has at least 40 wt.%, by way of example at least 50 wt.% (e.g., at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, or at least 90 wt.%) of oil of lubricating viscosity, based on the total weight of the composition. For example, the lubricating oil composition of the present disclosure may contain oil of lubricating viscosity between 40 wt.% and 95 wt.%, between 50 wt.% and 90 wt.%, or between 55 wt.% and 85 wt.%. Oil of lubricating viscosity may also be referred to as base oil.

[0041] According to certain embodiments of the present disclosure, the oil of lubricating viscosity has a kinematic viscosity at 100 °C of 4.0 mm 2 / s to less than 8.5 mm 2 / s. For example, the oil of lubricating viscosity may have a kinematic viscosity at 100 °C of 4.0 mm 2 / s to 8 mm 2 / s, or 4.5 mm 2 / s to 8 mm 2 / s, or 5.0 mm 2 / s to 7.5 mm 2 / s.

[0042] The lubricating viscosity oil of the present disclosure may contain only one base oil component or a mixture of two or more base oil components to achieve the above kinematic viscosity. The lubricating viscosity oil can be selected from any of Group I-V base oils specified in the American Petroleum Institute (API)'s Base Oil Interchangeability Guidelines (API Publication 1509). The five base oil groups are summarized in Table 1:

Table 1

[0043] Groups I, II, and III are mineral oil process stocks. Group IV base oils contain true synthetic molecular species produced by the polymerization of olefinically unsaturated hydrocarbons. Many Group V base oils are also true synthetic products and can include diesters, polyol esters, polyalkylene glycols, alkylated aromatics, polyphosphate esters, polyvinyl ethers, and / or polyphenyl ethers, etc., but can also be naturally occurring oils such as vegetable oils. Group III base oils are derived from mineral oils, but it should be noted that due to the strict treatment these fluids undergo, their physical properties are very similar to some true synthetic substances such as PAO. Therefore, oils derived from Group III base oils are sometimes called synthetic fluids in the industry.

[0044] The base oil used in the disclosed lubricating oil composition can be a mineral oil, animal oil, vegetable oil, synthetic oil, or a mixture thereof. Suitable oils can be derived from hydrocracked oils, hydrogenated oils, hydrofinished oils, unrefined oils, refined oils, and re-refined oils, and mixtures thereof.

[0045] Crude oil is oil derived from natural, mineral, or synthetic sources and has not been subjected to further refining or has been subjected to very little further refining. Refined oil is similar to crude oil, except that it has been processed in one or more refining steps, which may result in the improvement of one or more properties. Examples of suitable refining techniques include solvent extraction, secondary distillation, acid or base extraction, filtration, and osmosis. Oil refined to food quality may or may not be useful. Edible oil is sometimes also called white oil. In some embodiments, the lubricating oil composition does not contain edible oil or white oil.

[0046] Re-refined oil is also known as recycled oil or reprocessed oil. These oils are similarly obtained using the same or similar processes as refined oil. In many cases, these oils are further processed by techniques aimed at removing used additives and decomposition products of the oil.

[0047] Mineral oil may include oil obtained by drilling, or oil obtained from plants and animals, or any mixture thereof. Such oils include castor oil, lard oil, olive oil, peanut oil, corn oil, soybean oil, and linseed oil, as well as mineral lubricating oils, such as liquid petroleum, and paraffin-based, naphthenic-based, or mixed paraffin-based-naphthenic-based solvent-treated or acid-treated mineral lubricating oils. Such oils may be partially or fully hydrogenated as required. Oil derived from coal or shale may also be useful.

[0048] Useful synthetic lubricating oils include hydrocarbon oils such as polymerized, oligomerized, or interpolymerized olefins (e.g., polybutylene, polypropylene, propylene / isobutylene copolymer); poly(1 - hexene), poly(1 - octene), trimers or oligomers of 1 - decene such as poly(1 - decene) (such materials are often called α - olefins), and mixtures thereof; alkylbenzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di-(2 - ethylhexyl)-benzene); polyphenyls (e.g., biphenyl, terphenyl, alkylated polyphenyls); diphenylalkanes, alkylated diphenylalkanes, alkylated diphenyl ethers and alkylated diphenyl sulfides and their derivatives, analogs and homologs or mixtures thereof. Polyalphaolefins are typically hydrogenated materials.

[0049] Other synthetic lubricating oils include polyol esters, diesters, liquid esters of phosphorus - containing acids (e.g., tricresyl phosphate, trioctyl phosphate, and diethyl ester of decanephosphonic acid), or polymerized tetrahydrofuran. Synthetic oils may be produced by the Fischer - Tropsch reaction and may typically be hydrogen - isomerized Fischer - Tropsch hydrocarbons or waxes. In one embodiment, the oil may be prepared by Fischer - Tropsch gas - to - liquid synthesis procedures similar to other gas - to - liquid oils.

[0050] The base oils useful for the formulated lubricating oils disclosed herein can be any of a variety of oils corresponding to API Group I, Group II, Group III, Group IV, and Group V oils, and mixtures thereof. In one embodiment, the base oil is a Group II base oil or a blend of two or more different base oils. In another embodiment, the base oil is a Group I base oil or a blend of two or more different Group I base oils. Suitable Group I base oils include light overhead cuts from vacuum distillation columns, such as light neutral, medium neutral, and heavy neutral base stocks.

[0051] The base oil may also include residue base stocks or bottom fractions, such as bright stock by way of example. Bright stock is a high-viscosity base oil conventionally produced from residue stocks or bottoms and is highly refined and dewaxed. Bright stock can have a kinematic viscosity greater than 180 mm 2 / s at 40 °C (e.g., greater than 250 mm 2 / s, or even in the range of 500 - 1100 mm 2 / s). In certain embodiments, the lubricating oil composition does not contain bright stock.

[0052] Viscosity modifier According to this embodiment, a viscosity modifier can be added to the lubricating oil composition to increase the viscosity in order to obtain a finished lubricating oil composition having a desired viscosity grade. Surprisingly, in marine lubricants, replacing heavy neutral base oils and bright stock with a combination of lighter neutral base oils and an olefin copolymer viscosity modifier provides a lubricating oil composition with improved resistance to deposit formation and oxidation stability in engines operating under high-load conditions while achieving an appropriate lubricating oil viscosity.

[0053] According to embodiments of the present disclosure, suitable thickeners may include olefin copolymers (OCPs). Such additives are generally present on an active substance basis in an amount of 0.1 wt.% or more, such as 0.1 - 12 wt.%, of the lubricating oil composition. In certain embodiments, the OCP is present on an active substance basis in the lubricating oil composition in an amount of 0.2 - 10 wt.%, 0.3 - 9 wt.%, 0.4 - 8 wt.%, or 0.5 - 7 wt.%. In still further embodiments, the OCP is present on an active substance basis in the lubricating oil composition in an amount of 0.5 - 12.0 wt.%, 0.5 - 5 wt.%, or 1 - 2 wt.%. In still further embodiments, the OCP is present on an active substance basis in the lubricating oil composition in an amount of 1.0 wt.% or more, such as 1.0 - 12.0 wt.%, 1.0 wt.% - 5 wt.%, 1.3 wt.% - 4.5 wt.%, 1.5 wt.% - 4.0 wt.%, 2.0 - 12.0 wt.%, or 2.0 wt.% - 3.5 wt.%. In certain embodiments, the OCP is the only viscosity modifier or thickener present in the lubricating oil composition.

[0054] In certain embodiments, the olefin copolymer is a copolymer based on ethylene units and units of alpha-olefins (e.g., normal alpha-olefins, isomerized alpha-olefins), and by way of example, an ethylene-propylene copolymer composition. As other alpha-olefins suitable for forming terpolymers or tetrapolymers in place of propylene or in combination with ethylene and propylene, there may be mentioned, for example, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene; and branched-chain 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.

[0055] An olefin copolymer according to certain embodiments of the present invention advantageously has 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 and the stability of the formulation under stress. The molecular weight, in combination with the amounts referenced above, can provide a viscosity suitable for marine cylinders and TPEO lubricant compositions.

[0056] 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, by way of example 24 to 50, or 24 to 40.

[0057] An 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% based on the weight of the olefin copolymer. The olefin copolymer according to the present invention also 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% based on the number of moles of the olefin copolymer.

[0058] An olefin copolymer according to certain embodiments of the present invention may be a bimodal ethylene copolymer composition having a first ethylene copolymer fraction having a relatively low ethylene content; and a second ethylene copolymer fraction having a relatively high ethylene content. In one embodiment, the polymerization process used to produce the olefin copolymer is two or more alpha-olefin monomers (one of which is preferably ethylene; the other one is C3-C such as propylene in some embodiments) in the presence of one or more metallocene catalysts. 12It may include copolymerizing with an alpha-olefin (which may be an alpha-olefin). The olefin copolymers used in certain embodiments may include one or more olefin copolymers described in US20130203640, the disclosure of which is hereby incorporated by reference in its entirety.

[0059] In certain of these embodiments, the olefin copolymer composition of the present disclosure may include (a) a first ethylene-alpha olefin copolymer and (b) a second ethylene-alpha olefin copolymer. As an example, the first ethylene-alpha olefin copolymer (a) has an ethylene content of about 60 to about 80 wt% and can be referred to herein as a "semicrystalline" ethylene-alpha olefin copolymer. More typically, the ethylene content of the first ethylene-alpha olefin copolymer is about 63 to about 77 wt%, and even more typically, the ethylene content of the first ethylene-alpha olefin copolymer is about 65 to about 75 wt%. The second ethylene-alpha-olefin copolymer (b) has an ethylene content of less than about 60 wt%, more typically less than about 55 wt%, and even more typically about 42 to about 54 wt%, and is an ethylene-alpha-olefin copolymer that is less crystalline than the first ethylene-alpha-olefin copolymer (a) and can be referred to herein as an "amorphous" ethylene-alpha-olefin copolymer.

[0060] The first ethylene-alpha-olefin copolymer (a) has a melt flow rate ratio (MFRR) defined as the ratio of the MFR measured at 230 °C / 21.6 kg and 230 °C / 2.16 kg that is > 30, more typically up to about 55, even more typically about 33 to about 45, preferably > 34, more preferably about 34 to about 45, even more preferably about 35 to about 43. When the MFR conditions are also observed, the first ethylene-alpha-olefin copolymer (a) has an MFR that is at least about 1.5 g / 10 min, and in another embodiment, the MFR is at least about 1.6 g / 10 min. More typical ranges of the MFR are from about 1.5 g / 10 min to about 6.5 g / 10 min, and even more typical ranges are from about 2.5 g / 10 min to about 5.5 g / 10 min. The MFR is measured by ASTM D 1238 condition L (230 °C / 2.16 kg). In one embodiment, the first ethylene-alpha-olefin copolymer (a) has an MFRR > 30 and an MFR of at least about 1.5 g / 10 min. More preferably, the first ethylene-alpha-olefin copolymer (a) has an MFRR > 34 and an MFR of at least about 1.6 g / 10 min.

[0061] In one embodiment, the olefin copolymer composition contains about 30 wt% to about 70 wt% of the first ethylene-alpha-olefin copolymer (a) and about 70 wt% to about 30 wt% of the second ethylene-alpha-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 wt% to about 60 wt% of the first ethylene-alpha-olefin copolymer (a) and about 60 wt% to about 40 wt% of the second ethylene-alpha-olefin copolymer (b), based on the total amount of (a) and (b) in the composition. In a particular embodiment, the olefin copolymer composition contains about 50 wt% to about 54 wt% of the first ethylene-alpha-olefin copolymer (a) and about 46 wt% to about 50 wt% of the second ethylene-alpha-olefin copolymer (b), based on the total amount of (a) and (b) in the composition.

[0062] In one embodiment, the weight average molecular weight of the first ethylene-alpha-olefin copolymer is from about 60,000 to about 120,000. In another embodiment, the weight average molecular weight of the first ethylene-alpha-olefin copolymer is from about 70,000 to about 110,000. In one embodiment, the weight average molecular weight of the second ethylene-alpha-olefin copolymer is from about 60,000 to about 120,000. In another embodiment, the weight average molecular weight of the second ethylene-alpha-olefin copolymer is from about 70,000 to about 110,000.

[0063] In one embodiment, the weight average molecular weight of the composition of the first ethylene-alpha-olefin copolymer and the second ethylene-alpha-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-alpha-olefin copolymer and the second ethylene-alpha-olefin copolymer is from about 70,000 to about 110,000. In yet a further embodiment, the weight average molecular weight of the composition of the first ethylene-alpha-olefin copolymer and the second ethylene-alpha-olefin copolymer is from about 80,000 to about 100,000. The molecular weight distribution of each of the ethylene-alpha-olefin copolymers can be less than about 2.5, and more typically, from about 2.1 to about 2.4. The polymer distribution determined by GPC for each of the ethylene-alpha-olefin copolymers is typically unimodal.

[0064] Other performance additives The lubricant composition of the present invention may contain one or more performance additives that can impart or improve any desired property of the lubricant composition. Any additive known to those skilled in the art can be used in the lubricant composition disclosed herein. Some suitable additives are described in R. M. Mortier et al., “Chemistry and Technology of Lubricants,” 3rd Edition, Springer (2010) and L. R. Rudnik, “Lubricant Additives: Chemistry and Applications,” Second Edition, CRC Press (2009).

[0065] Generally, the concentration of each additive in the lubricant composition, when used, can 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 lubricant composition. When diluent oil is included, each of the additives in the lubricant composition can be in the range of 0.5 to 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 lubricant composition. Further, the total amount of additives in the lubricant composition can 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 lubricant composition. When diluent oil is included, the total amount of additives in the lubricant composition can be in the range of 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 lubricant composition.

[0066] By way of example, the lubricant composition of the present invention may contain one or more lubricant performance additives including detergents, dispersants, anti-wear agents, antioxidants, friction modifiers, corrosion inhibitors, rust inhibitors, demulsifiers, foam inhibitors, viscosity modifiers, pour point depressants, nonionic surfactants, thickeners, and the like. Some of these will be considered in more detail below.

[0067] Detergent The lubricating oil composition of the present disclosure may contain one or more detergents. A detergent is an additive that reduces the formation of piston deposits, such as high-temperature varnish and lacquer deposits in an engine. Detergents generally have acid-neutralizing properties, and most detergents that can hold finely divided solids in suspension are metal salts of acidic organic compounds.

[0068] Both metal-containing or ash-forming detergents function as detergents to reduce or remove deposits and as acid neutralizers or rust inhibitors, thereby reducing wear and corrosion and extending the life of the engine. Detergents generally contain a polar head together with a long hydrophobic tail. The polar head contains a metal salt of an acidic organic compound.

[0069] In the art, detergents are generally referred to as neutral or overbased. Detergents containing substantially stoichiometric amounts of metal salts are usually described as normal or neutral detergents. In embodiments where large amounts of metal bases are incorporated into the detergent by reacting excess metal compounds (e.g., oxides or hydroxides) with acidic gases (e.g., carbon dioxide), the detergent is called overbased.

[0070] Overbased metal detergents are generally produced by carbonating (using CO2) a mixture of a hydrocarbon, a detergent acid (e.g., sulfonic acid or carboxylate), a metal oxide or hydroxide (e.g., calcium oxide or calcium hydroxide), and an accelerator, such as xylene, methanol, and / or water. For example, when preparing overbased calcium sulfonate, in the carbonation, calcium oxide or calcium hydroxide reacts with gaseous carbon dioxide to form calcium carbonate. The sulfonic acid is neutralized with excess CaO or Ca(OH)2 to form sulfonate.

[0071] Overbased detergents can be further characterized as low overbased, medium overbased, or high overbased. A low overbased detergent can be, for example, an overbased salt 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.

[0072] A medium overbased detergent can be, for example, an overbased salt having a TBN of from about 100 to about 250. In one embodiment, the TBN of the medium overbased salt can be from about 100 to about 200. In another embodiment, the TBN of the medium overbased salt can be from about 125 to about 175.

[0073] A high overbased detergent can be, for example, an overbased salt having a TBN greater than 250. In one embodiment, the TBN of the high overbased salt can be from about 250 to about 800.

[0074] Compounds that may be used as detergents include neutral and overbased oil-soluble sulfonates, phenates, sulfurized phenates, thiophosphonates, salicylates, and naphthenates of metals, particularly alkali metals or alkaline earth metals such as barium, sodium, potassium, lithium, calcium, and magnesium, as well as other oil-soluble carboxylates. The most commonly used metals are calcium and magnesium, both of which can be present in detergents used in lubricants, as well as in mixtures of calcium and / or magnesium with sodium.

[0075] In one embodiment, the detergent can be one or more alkali metal or alkaline earth metal salts of alkyl-substituted hydroxyaromatic carboxylic acids, which are carboxylates or salicylates. Suitable hydroxyaromatic compounds include mononuclear mono-hydroxy and poly-hydroxy aromatic hydrocarbons having 1 to 4, preferably 1 to 3, hydroxyl groups.

[0076] Suitable hydroxyaromatic compounds include phenol, catechol, resorcinol, hydroquinone, pyrogallol, cresol, and the like. In certain embodiments, the preferred hydroxyaromatic compound is phenol.

[0077] The alkyl substitution site 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 used can be linear, isomerized linear, branched, or partially branched linear. 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 any mixture of the foregoing.

[0078] In some embodiments, the mixture of linear olefins is a mixture of normal alpha olefins selected from olefins having 10 to 40 carbon atoms per molecule. In one embodiment, the normal alpha olefin is isomerized using at least one of a solid catalyst or a liquid catalyst.

[0079] In one embodiment, 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 or alkaline earth metal salts of alkyl-substituted hydroxyaromatic carboxylic acids, such as the alkyl group of the alkaline earth metal salt of the alkyl-substituted hydroxybenzoic acid detergent, are C 20 alkyl substituents as described above. In certain of these embodiments, the alkali metal salt or alkaline earth metal salt of the alkyl-substituted hydroxyaromatic carboxylic acid has at least 75 mol% of the alkyl group as C 20 -C 28It is an alkali metal salt or alkaline earth metal salt of an alkyl-substituted hydroxybenzoic acid derived from an alkyl-substituted hydroxybenzoic acid residue of a normal alpha-olefin containing a normal alpha-olefin. 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 group of the alkali metal salt or alkaline earth metal salt of the alkyl-substituted hydroxybenzoic acid is C 20 -C 24 an alkyl substituent.

[0080] 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 group of the alkali metal salt or alkaline earth metal salt of the alkyl-substituted hydroxybenzoic acid is C 14 -C 18 an alkyl substituent. In another embodiment, the alkali metal salt or alkaline earth metal salt of the alkyl-substituted hydroxyaromatic carboxylic acid is isomerized 10 -C 40 a normal alpha-olefin, isomerized C 20 -C 28 a normal alpha-olefin, or preferably isomerized C 20 -C 24 derived from an alkyl group having a normal alpha-olefin. In one embodiment, the isomerized normal alpha-olefin has an isomerization level of the alpha-olefin that is between about 0.1 and about 0.4. In another embodiment, the alkyl group is derived from at least two alkylphenols. The alkyl group on at least one of the at least two alkylphenols is derived from an isomerized alpha-olefin. The alkyl group on the second alkylphenol can be derived from a branched or partially branched olefin, a highly isomerized olefin, or a mixture thereof.

[0081] The alkyl substitution moiety of the alkali metal salt or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid can be derived from cashew nut shell liquid (CNSL) or hydrodistilled CNSL. Distilled CNSL is a biodegradable meta-hydrocarbyl-substituted phenol mixture containing cardanol, where the hydrocarbyl group is linear and unsaturated. Contact hydrogenation of distilled CNSL yields a mixture of meta-hydrocarbyl-substituted phenols rich mainly in 3-pentadecylphenol.

[0082] The alkali metal salt or alkaline earth metal salt of an 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% ortho isomer and 99 to 1% para isomer. In another embodiment, the alkyl-substituted hydroxyaromatic carboxylic acid can contain about 5 to 70% ortho isomer and 95 to 30% para isomer.

[0083] The alkali metal salt or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid may be neutral or overbased. Generally, an overbased alkali metal salt or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid has an increased TBN of the alkali metal salt or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid by a process such as the addition of a base source (e.g., lime) and an acidic overbasing compound (e.g., carbon dioxide).

[0084] As described above, in certain embodiments of the lubricating oil composition, one or more sulfonate detergents can be used, either alone or in combination with other detergents. The sulfonates can be prepared from sulfonic acids obtained by fractionation of petroleum or by sulfonation of alkyl-substituted aromatic hydrocarbons obtained 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 halogen derivatives thereof. The alkylation can be carried out in the presence of a catalyst using an alkylating agent having from 3 to over 70 carbon atoms. Alkaryl sulfonates typically contain from 9 to over 80 carbon atoms, preferably from 16 to 60 carbon atoms, preferably from 16 to 30 carbon atoms, and most preferably from 20 to 24 carbon atoms per alkyl-substituted aromatic moiety.

[0085] The oil-soluble sulfonates or alkali sulfonic acids can be neutralized with metal oxides, hydroxides, alkoxides, carbonates, carboxylates, sulfides, hydrosulfides, nitrates, borates, and ethers. The amount of the metal compound is selected in consideration of the desired TBN of the final product.

[0086] Metal salts of phenols and sulfurized phenols (e.g., phenate or sulfurized phenate detergents) are prepared by reaction of a phenol or sulfurized phenol with a suitable metal compound such as an oxide or hydroxide. Sulfurized phenols can be prepared by reacting a phenol with sulfur or a sulfur-containing compound such as hydrogen sulfide, monohalogenated sulfur, or dihalogenated sulfur to form a product that is typically a mixture of compounds in which two or more phenols are bridged by sulfur-containing linkages. Further details regarding the general preparation of sulfurized phenates are described, for example, in U.S. Patent Nos. 2,680,096; 3,178,368, and 3,801,507, the contents of which are incorporated herein by reference.

[0087] The sulfur used for the formation of the sulfurized compound may have any allotropic form of sulfur. The sulfur may be present either as molten sulfur or as a solid (e.g., powder or particles) or as a solid suspension in a compatible hydrocarbon liquid.

[0088] In some embodiments, it is desirable to use calcium hydroxide as the calcium base since it is easy to handle and gives excellent results with respect to, for example, calcium oxide. Other calcium bases such as calcium alkoxides can also be used.

[0089] Suitable alkylphenols that can be used are those in which the alkyl substituent contains a sufficient number of carbon atoms such that the resulting alkylphenate (e.g., overbased calcium sulfonate alkylphenate) composition is oil-soluble. The oil solubility can be provided by a single long-chain alkyl substituent or by a combination of alkyl substituents. Typically, the alkylphenols used are mixtures of different alkylphenols, e.g., C 20 -C 24 alkylphenol mixtures. In one embodiment, a suitable alkylphenol compound is derived from an isomerized normal alpha olefin alkyl group having from about 10 to about 40 carbon atoms per molecule and an isomerization level of alpha olefin between about 0.1 and about 0.4. In one embodiment, the isomerized normal alpha olefin has from about 20 to about 24 carbon atoms. In one embodiment, a suitable alkylphenol compound is derived from an alkyl group that is a branched-chain olefin propylene oligomer or a mixture thereof having from about 9 to about 80 carbon atoms. In one embodiment, the branched-chain olefin propylene oligomer or mixture thereof has from about 9 to about 40 carbon atoms. In one embodiment, the branched-chain olefin propylene oligomer or mixture thereof has from about 9 to about 18 carbon atoms. In one embodiment, the branched-chain olefin propylene oligomer or mixture thereof has from about 9 to about 12 carbon atoms.

[0090] In one embodiment, suitable alkylphenol compounds include distilled cashew nut shell liquid (CNSL) or hydrogenated distilled CNSL. Distilled CNSL is a mixture of biodegradable meta-hydrocarbyl-substituted phenols containing cardanol, in which the hydrocarbyl groups are linear and unsaturated. The catalytic hydrogenation of distilled CNSL yields a mixture of meta-hydrocarbyl-substituted phenols rich mainly in 3-pentadecylphenol.

[0091] The alkylphenol can be para-alkylphenol, meta-alkylphenol or orthoalkylphenol. In certain embodiments such as when an overbased product is desired, the alkylphenol is preferably mainly paraalkylphenol, with no more than about 45 mole percent of the alkylphenol being orthoalkylphenol; more preferably no more than about 35 mole percent of the alkylphenol being orthoalkylphenol. Alkyl-hydroxytoluene or xylene, and other alkylphenols having one or more alkyl substituents in addition to at least one long-chain alkyl substituent can also be used. In the case of distilled cashew nut shell liquid, the catalytic hydrogenation of distilled CNSL yields a mixture of meta-hydrocarbyl-substituted phenols.

[0092] Generally, the selection of the alkylphenol can be made based on the properties desired for the marine diesel engine lubricating oil composition, particularly TBN and oil solubility. Additional information regarding 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.

[0093] Generally, the amount of the detergent can be from about 0.001 wt.% to about 50 wt.%, or from about 0.05 wt.% to about 25 wt.%, or from about 0.1 wt.% to about 20 wt.%, or from about 0.01 to 15 wt.%, based on the total weight of the marine diesel lubricating oil composition.

[0094] The detergent may also include "hybrid" or "composite" detergents formed from mixed surfactant systems containing a phenate and / or sulfonate component, such as, for example, phenate / salicylate, sulfonate / phenate, sulfonate / salicylate, sulfonate / phenate / salicylate, etc., as described, for example, in U.S. Patent Nos. 6,429,178; 6,429,179; 6,153,565. The detergent may also include a methylene-bridged polyphenol composition prepared from the reaction of phenol and formaldehyde, or its reversible polymer, and optionally, sulfiding the methylene-bridged intermediate followed by reacting the intermediate with an excess of 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.

[0095] Other detergents can be present in any suitable amount, such as 0.1 to 45 wt.%, or 0.5 to 30 wt.% of the lubricating oil composition.

[0096] Dispersant The lubricant composition of the present disclosure may include one or more dispersants. During engine operation, oil-insoluble oxidation by-products are generated. The dispersant helps to keep these by-products in solution and thus reduces their deposition on metal surfaces. Dispersants are often known as ashless dispersants because they do not contain ash-forming metals before being mixed into the lubricating oil composition and usually do not produce ash when added to the lubricant. Ashless dispersants are characterized by polar groups attached to relatively high molecular weight or high molecular weight hydrocarbon chains. Typical ashless dispersants include N-substituted long-chain alkenyl succinimides. Examples of N-substituted long-chain alkenyl succinimides include polyisobutylene succinimides in which the number average molecular weight of the polyisobutylene substituent 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. Pat. Nos. 4,234,435 and 7,897,696. Succinimide dispersants are typically imides formed from polyamines, typically poly(ethyleneamine).

[0097] 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 may be used alone or in combination with other dispersants.

[0098] The dispersant may also be post-treated by reacting it with any of various agents by conventional methods. These agents include boron compounds (e.g., boric acid) and cyclic carbonates (e.g., ethylene carbonate).

[0099] Another class of dispersants includes Mannich bases. Mannich bases are materials formed by the condensation of high molecular weight alkyl-substituted phenols, polyalkylene polyamines, and aldehydes such as formaldehyde. Mannich bases are described in detail in U.S. Pat. No. 3,634,515.

[0100] Another class of dispersants includes high molecular weight esters prepared by the reaction of a hydrocarbyl acylating agent with a polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or sorbitol. Such materials are described in detail in U.S. Patent No. 3,381,022.

[0101] Another class of dispersants includes high molecular weight ester amides.

[0102] The dispersant can be present in the lubricating oil composition at 0.1 to 15 wt.%.

[0103] Antiwear agent Antiwear agents reduce friction and excessive wear and are typically based on compounds containing sulfur or phosphorus or both. Of note are the dihydrocarbyl dithiophosphate metal salts, where the metal can be an alkali metal or alkaline earth metal, or aluminum, lead, tin, molybdenum, manganese, nickel, copper, or zinc. Zinc dihydrocarbyl dithiophosphate (ZDDP) is an oil-soluble salt of dihydrocarbyl dithiophosphoric acid and can be represented by the following formula: Zn[SP(S)(OR)(OR’)]2 (wherein R and R’ can be the same or different hydrocarbyl groups containing from 1 to 18 (e.g., 2 to 12) carbon atoms). To obtain oil solubility, the total number of carbon atoms in the dithiophosphoric acid (i.e., R and R’) is generally 5 or more.

[0104] The antiwear agent can be present in the lubricating oil composition at 0.1 to 6 wt.%.

[0105] Antioxidant Antioxidants retard the decomposition of the base oil during use due to oxidation. Such decomposition can lead to deposition on metal surfaces, the presence of sludge, or an increase in the viscosity of the lubricant.

[0106] Useful antioxidants include hindered phenols. Hindered phenol antioxidants often contain secondary butyl groups and / or tertiary butyl groups as steric hindrance groups. The phenol group may be further substituted with a hydrocarbyl group (typically a straight or branched chain alkyl) and / or a crosslinking group bonded 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-dialkyl-phenolpropionate esters, and bisphenols such as 4,4'-bis(2,6-di-tert-butylphenol) and 4,4'-methylene-bis(2,6-di-tert-butylphenol).

[0107] Alkylphenol sulfides and their alkali metal salts and alkaline earth metal salts are also useful as antioxidants.

[0108] 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.

[0109] The antioxidant can be present in the lubricating oil composition at 0.01 to 15.0 wt.%.

[0110] Friction modifier A friction modifier is any material that can change the coefficient of friction of a surface lubricated by any lubricant or fluid containing such a material. Suitable friction modifiers include fatty amines, esters such as borated glycerol esters, 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 "fatty" with respect to a friction modifier means a carbon chain having 10 to 22 carbon atoms, typically a straight-chain carbon chain. Molybdenum compounds are also known as friction modifiers. The friction modifier can be present in the lubricating oil composition at 0.01 to 10.0 wt.%.

[0111] Rust inhibitor Rust inhibitors generally protect lubricated metal surfaces from chemical attack by water or other contaminants. Suitable rust inhibitors may include nonionic polyoxyalkylene agents such as polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl 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 polyhydric alcohols; phosphate esters; (short-chain) alkenyl succinic acids, partial esters thereof, and nitrogen-containing derivatives thereof; and synthetic alkylaryl sulfonates (e.g., metal salts of dinonylnaphthalene sulfonic acid). Such additives can be present in the lubricating oil composition at 0.01 to 5 wt.%.

[0112] Demulsifier An anti-emulsifier promotes oil-water separation in lubricating oil compositions exposed to water or steam. Suitable anti-emulsifiers include trialkyl phosphates, as well as various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof. Such additives can be present in the lubricating oil composition at 0.01 to 5 wt.%.

[0113] Anti-foaming agent An anti-foaming agent delays the formation of stable bubbles. Silicones and organic polymers are typical anti-foaming agents. For example, polysiloxanes, such as silicone oil or polydimethylsiloxane, provide foam suppression properties. Further anti-foaming agents include copolymers of ethyl acrylate and 2-ethylhexyl acrylate, and optionally vinyl acetate. Such additives can be present in the lubricating oil composition at 0.001 to 1 wt.%.

[0114] Viscosity modifier A viscosity modifier gives the lubricant operability at high and low temperatures. These additives impart shear stability at high temperatures and an acceptable viscosity at low temperatures. Suitable viscosity modifiers include polyolefins, olefin copolymers (OCPs), ethylene / propylene copolymers, polyisobutene, hydrogenated styrene-isoprene polymers, styrene / maleic ester copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkylstyrenes, and hydrogenated alkenylaryl conjugated diene copolymers. Such additives can be present in the lubricating oil composition at 0.1 to 15 wt.%.

[0115] Pour point depressant The pour point depressant lowers the lowest temperature at which a fluid can flow or can be poured. Examples of suitable pour point depressants include polymethacrylates, polyacrylates, polyacrylamides, condensation products of haloparaffin waxes and aromatic compounds, vinyl carboxylate polymers, and terpolymers of dialkyl fumarates, vinyl esters of fatty acids, and allyl vinyl ethers. Such additives can be present in the lubricating oil composition at 0.01 to 1.0 wt.%.

[0116] Nonionic surfactant Nonionic surfactants such as alkylphenols can improve the handling of asphaltenes during engine operation. Examples of such materials include alkylphenols having an alkyl substituent from a straight-chain or branched-chain alkyl group having 9 to 30 carbon atoms. Other examples include alkylbenzenols, alkylnaphthols, and alkylphenol aldehyde condensates (where the aldehyde is formaldehyde and thus the condensate is a methylene-bridged alkylphenol). Such additives can be present in the lubricating oil composition at 0.1 to 20 wt.%.

[0117] Marker The lubricating oil composition of the present invention may contain a dye or marker component, such as a tracer, which are particularly suitable for marking the lubricant to protect brand equity, prevent misidentification, and assist in the identification of 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 or are currently used for marking or tagging lubricants include colorants and fluorescent dyes (e.g., diazo dyes, anthraquinone dyes, phthalain dyes, etc.), radioactive substances, metal compounds or complexes (metal-organic compounds, metal salts, metal oxides, metal coordination complexes, etc.), and various specific compounds that react with a selected agent to provide a dark-colored derivative.

[0118] 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. Certain metal soaps, metal soaps of fatty acids, metal carboxylates, or materials such as known metal desiccants 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 are also useful as lubricant markers. Examples of zirconium-containing materials include zirconium carboxylate materials such as zirconium 2-ethylhexanoate, zirconium octoate, and zirconium salicylate materials.

[0119] Use of the lubricating oil composition The lubricant composition can be effective as a lubricating oil for compression ignition internal combustion engines including marine diesel engines, stationary gas engines, and the like.

[0120] The internal combustion engine may be a two-stroke or four-stroke engine.

[0121] In one embodiment, the internal combustion engine is a marine diesel engine. The marine diesel engine may be a medium-speed four-stroke compression ignition engine having a speed of 250 to 1100 rpm, or a low-speed crosshead two-stroke compression ignition engine having a speed of 200 rpm or less (e.g., 60 to 200 rpm).

[0122] The marine diesel engine can be lubricated with a marine diesel cylinder lubricant (typically for a two-stroke engine), system oil (typically for a two-stroke engine), or crankcase lubricant (typically for a four-stroke engine).

[0123] The term "marine" is not limited to engines used in water-borne vessels; as understood in the art, it also includes those for other industrial applications such as auxiliary power generation for main propulsion and stationary land engines for power generation.

[0124] In some embodiments, the internal combustion engine can 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.

[0125] The internal combustion engine can also be operable with "gaseous fuels", such as methane-based fuels (e.g., natural gas), biogas, gasified liquefied gas, or gasified liquefied natural gas (LNG) by way of example.

Examples

[0126] The following exemplary examples are to be considered non-limiting.

[0127] The following components were used in formulating the marine lubricant compositions of the examples. Generally, the marine lubricant compositions of the examples included an oil of lubricating viscosity (base oil component), a thickener, and an additive package.

[0128] The base oil components used in the formulations of the examples included the following:

[0129] XOM 150N: ExxonMobil CORE® 150N Group I lubricating oil, kv at 100 °C is 5.1 mm 2 / s

[0130] XOM 600N: ExxonMobil CORE® 600N Group I lubricating oil, kv at 100 °C is 12.4 mm 2 / s

[0131] XOM 2500BS: ExxonMobil CORE® 2500BS Group I lubricating oil, kv at 100 °C is 30.6 mm 2 / s

[0132] RLOP 100R: Chevron Group II lubricant, kinematic viscosity (kv) at 100 °C is 4.4 mm 2 / s

[0133] RLOP 220R: Chevron 220 RLOP: Group II lubricant, kinematic viscosity (kv) at 100 o °C is 6.4 mm 2 / s

[0134] RLOP 600R: Chevron 600R RLOP: Group II lubricant, kinematic viscosity (kv) at 100 °C is 12.0 mm 2 / s

[0135] The olefin copolymer thickeners used in the formulations of the examples were concentrates of olefin copolymers, specifically ethylene-propylene copolymers, in diluents. Thus, in the tables shown below, the weight percentages listed for the OCP thickeners are based on the as-received state, not on the active substance basis. To obtain the weight percentage on an active substance basis of the olefin copolymer, it is necessary to multiply the weight percentage listed for the OCP thickener by the weight percentage of the olefin copolymer present in the OCP thickener.

[0136] OCP-1: Concentrate having 6.30 wt.% of a 50 SSI olefin copolymer in Group II diluent oil, the 50 SSI olefin copolymer containing 60% ethylene and having a number average molecular weight (Mn) of 112,000 g / mol.

[0137] OCP-2: Concentrate having 10.00 wt.% of a 24 SSI olefin copolymer in Group II diluent oil, the 24 SSI olefin copolymer containing 57% ethylene and having a number average molecular weight (Mn) of 40,000 g / mol.

[0138] OCP-3: A concentrate having 18.75 wt.% of a 35 SSI olefin copolymer in Group II diluent oil, the 35 SSI olefin copolymer containing 57% ethylene and having a number average molecular weight (Mn) of 49,000 g / mol.

[0139] OCP-4: A concentrate having 8.6 wt.% of a 50 SSI olefin copolymer in Group II diluent oil, the 50 SSI olefin copolymer containing 49% ethylene and having a number average molecular weight (Mn) of 84,000 g / mol.

[0140] The additive packages used in the formulations of the examples included the following:

[0141] Additive package A: An oil concentrate of a high TBN calcium sulfonate detergent, an oil concentrate of a MOB calcium sulfide phenate detergent, an oil concentrate of a LOB calcium sulfide phenate detergent, an oil concentrate of a succinimide dispersant, a tracer component, and an anti-foaming agent.

[0142] Additive package B: C 20 -C 24 A 7.5 wt.% oil concentrate (33.0 wt.% diluent oil) of a 410 BN overbased calcium carboxylate detergent derived from isomerized alpha olefins, C 20 -C 24 A 5.2 wt.% oil concentrate (20 wt.% diluent oil) of a 180 BN overbased calcium carboxylate detergent derived from isomerized normal alpha olefins, 0.7 wt.% zinc dialkyldithiophosphate, and 0.1 wt.% anti-foaming agent.

[0143] Additive package C: A 6.92 wt. oil concentrate (38.7 w.% diluent oil) of a 420 BN calcium sulfonate detergent, a 6.0 wt% oil concentrate (50.0 wt.% diluent oil) of a 17 BN calcium sulfonate detergent, C 20 -C 249.0 wt.% oil concentrate (diluent oil 20 wt.%) of 95BN calcium sulfonate phenate detergent derived from isomerized alpha olefin, 0.2 wt.% oil concentrate (diluent oil 32 wt.%) of bisuccinimide dispersant derived from 1000MW PIB, 1.5 wt.% antioxidant, 0.11 wt.% foam inhibitor and diluent oil.

[0144] Additive Package D:C 20 -C 24 5.0 wt.% oil concentrate (diluent oil 40 wt.%) of 260BN calcium sulfonate phenate detergent derived from isomerized alpha olefin, C 20 -C 24 4.0 wt.% oil concentrate (diluent oil 33.0 wt.%) of 410BN overbased calcium carboxylate detergent derived from isomerized alpha olefin, C 20 -C 24 5.45 wt.% oil concentrate (diluent oil 20 wt.%) of 180BN overbased calcium carboxylate detergent derived from isomerized normal alpha olefin, 0.2 wt.% oil concentrate (diluent oil 32 wt.%) of bisuccinimide dispersant derived from 1000MW PIB, 1.5 wt.% antioxidant, 0.11 wt.% foam inhibitor and diluent oil.

[0145] For the following examples, the degree of high-temperature detergency and oxidation stability was evaluated using the tests described below. The results of each of the examples are shown in Tables 2 to 5.

[0146] Test Method Microcoker This method is used to evaluate the high-temperature deposit / lacquer formation tendency of lubricants for land and marine applications. A fixed amount of test oil is placed in a shallow groove of an inclined aluminum panel. A temperature gradient is applied to the aluminum panel while the test oil is uniformly dispersed in the shallow groove. The panel is heated and the deposit / lacquer formation onset temperature is determined from the appearance of the panel at the end of the test.

[0147] DSC Oxidation Test The DSC test is used to evaluate the thin-film oxidation stability of the test oil in accordance with ASTM D-6186. During the test, the heat flow to the test oil in the sample cup and the heat flow from the test oil are compared with the reference cup. The oxidation onset temperature is the temperature at which the oxidation of the test oil begins. The oxidation induction time is the time at which the oxidation of the test oil begins. The longer the oxidation induction time, the better the performance. The oxidation reaction is exothermic and is clearly indicated by the heat flow. The oxidation induction time is calculated to evaluate the thin-film oxidation stability of the test oil.

[0148] Modified Institute of Petroleum 48 (MIP-48) test The MIP-48 test consists of a heat part and an oxidation part. In both parts of the test, the test sample is heated. In the heat part of the test, nitrogen passes through the heated oil sample for 24 hours, and in parallel, in the oxidation part of the test, air passes through the heated oil sample for 24 hours. The sample is cooled and the viscosities of both samples are determined. The increase in viscosity of the test oil due to oxidation is determined and the effect of heat is corrected. The oxidation-based viscosity increase for each marine lubricating oil composition is calculated by subtracting the kinematic viscosity at 200 °C of the nitrogen-blown sample from the kinematic viscosity at 200 °C of the air-blown sample and dividing the subtraction product by the kinematic viscosity at 200 °C of the nitrogen-blown sample. This is done to correct for potential evaporation effects or other heat effects during the test, thereby focusing on the effect of oxidation. This correction may result in a negative value. Test oils that exhibit better stability with respect to the oxidation-based viscosity increase result in lower % absolute value results.

[0149] Results Examples 1 to 4, and Comparative Example A Examples 1 to 4 and Comparative Example A were prepared using 20.0 wt.% of Additive Package A in a 70 BN, SAE 50 viscosity grade (kv at 100 °C is 19.5 mm 2It was blended into the cylinder lubricant composition for ships of ( / s). Comparative Example A was blended using a combination of a more common heavy neutral oil RLOP600R and XOM2500BS bright stock to achieve an appropriate lubricating oil viscosity. Each of Examples 1 to 4 contained a combination of a light neutral oil RLOP100R and an olefin copolymer thickener to achieve an appropriate lubricating oil viscosity for the finishing lubricant. The listed weight percentages for the OCP thickener are based on the as-received state. The microcoker and DSC oxidation tests were used to evaluate each of the lubricants for high-temperature detergency and oxidation performance. The results of each of the examples are shown in Table 2 below.

Table 2

[0150] The results shown in Table 2 indicate that the cylinder lubricant composition for ships containing a combination of a light neutral oil RLOP100R and an olefin copolymer thickener exhibited surprisingly excellent detergency and oxidation performance compared to Comparative Example A. This performance improvement is demonstrated by the fact that the lacquer formation temperature is higher and the oxidation induction time is longer in the examples of the present invention compared to the comparative examples. Furthermore, Examples 1 to 4 were formulated to achieve an SAE50 viscosity grade without using a heavy neutral oil and without using bright stock in the finishing lubricant composition.

[0151] Comparative Example B Examples 5 and Comparative Example B were 40BN, SAE40 viscosity grade (kv at 100 °C is 14.0 mm) containing 13.5 wt% of additive package B 2It was formulated into a trunk piston engine lubricating oil composition for ships ( / s). Comparative Example B was formulated using a combination of a more common heavy neutral oil 600R and XOM2500BS bright stock to achieve an appropriate lubricating oil viscosity. Example 5 contained a combination of a light neutral oil 220R and an olefin copolymer thickener to achieve an appropriate lubricating oil viscosity for the finishing lubricant. The listed weight percentages for the OCP thickener are based on the as-received state. Each of the lubricants was evaluated for oxidation stability using the DSC oxidation test. The results of each of the examples are shown in Table 3 below.

Table 3

[0152] The results in Table 3 show that the trunk piston engine lubricating oil composition containing a combination of light neutral oil 220R and an olefin copolymer thickener exhibited surprisingly excellent oxidation performance compared to Comparative Example B. This performance improvement is demonstrated by the longer oxidation induction time of Example 5 compared to Comparative Example B. Further, Example 5 was formulated to achieve an SAE40 viscosity grade without using heavy neutral oil and bright stock in the finishing lubricating oil composition.

[0153] Example 6 and Comparative Example C Example 6 and Comparative Example C contain 24.98 wt.% of additive package C, a 40 BN, SAE50 viscosity grade (kv at 100 °C is 18.5 mm 2It was formulated in a cylinder lubricating oil composition for ships of ( / s). Comparative Example C was formulated using a combination of a more common heavy neutral oil 600R and XOM2500BS bright stock to achieve an appropriate lubricating oil viscosity. Example 6 contained a combination of a light neutral oil 220R and an olefin copolymer thickener to achieve an appropriate lubricating oil viscosity for the finishing lubricant. The listed weight percentages for the OCP thickener are based on the as-received state. Each of the lubricants was evaluated for oxidation stability using a DSC oxidation test. The results of each of the examples are shown in Table 4 below.

Table 4

[0154] The results in Table 4 show that the cylinder lubricating oil composition for ships containing a combination of a light neutral oil 220R and an olefin copolymer thickener exhibited surprisingly excellent oxidation performance compared to Comparative Example C. This performance improvement is demonstrated by the longer oxidation induction time of Example 6 compared to Comparative Example C. Further, Example 6 was formulated to achieve an SAE50 viscosity grade without using heavy neutral oil and bright stock in the finishing lubricating oil composition.

[0155] Example 7 and Comparative Example D Example 7 and Comparative Example D were formulated in a cylinder lubricating oil composition for ships of 40BN, SAE50 viscosity grade (kv at 100 °C is 18.5 mm 2 / s) containing 17.12 wt.% of additive package D. Comparative Example D was formulated using a combination of a more common heavy neutral oil 600R and XOM2500BS bright stock to achieve an appropriate lubricating oil viscosity. Example 7 contained a combination of a light neutral oil 220R and an olefin copolymer thickener to achieve an appropriate lubricating oil viscosity for the finishing lubricant. The listed weight percentages for the OCP thickener are based on the as-received state. Each of the lubricants was evaluated for oxidation stability using a DSC oxidation test. The results of each of the examples are shown in Table 5 below.

Table 5

[0156] The results in Table 5 show that the marine cylinder lubricant composition containing the combination of light neutral oil 220R and an olefin copolymer thickener exhibited surprisingly excellent oxidation performance compared to Comparative Example D. This performance improvement is demonstrated by the longer oxidation induction time of Example 7 compared to Comparative Example D. Furthermore, Example 7 was formulated to achieve an SAE 50 viscosity grade without using heavy neutral oil and bright stock in the finished lubricant composition.

[0157] It should be understood that the above specific embodiments are presented by way of example, and that these embodiments are capable of various modifications and alternative forms, and can also be used in any suitable combination. The claims are not intended to be limited to the specific forms disclosed, but rather are to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

Claims

1. A lubricating oil composition for a marine diesel engine, comprising: (a) an oil having a lubricating viscosity with a kinematic viscosity at 100 °C of less than 4.0 to 8.5 mm ２ / s and comprising at least 40 wt.%; and (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000; The lubricating oil composition for a marine diesel engine has a TBN exceeding 30 mg KOH / g, and further, the lubricating oil composition for a marine diesel engine is a monograde lubricating oil composition that meets the specifications of SAE J300 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 an ethylene unit content in the range of 30% to 80% by weight based on the weight of the (said) olefin copolymer.

3. The composition according to claim 1, wherein the one or more olefin copolymers are present in the lubricating oil composition at 0.5 to 5 wt.% on an active substance basis.

4. The composition according to claim 1, wherein the one or more olefin copolymers are present in the lubricating oil composition at 1 to 2 wt.% on an active substance basis.

5. The composition according to claim 1, wherein the one or more olefin copolymers are the only viscosity modifier present in the lubricating oil composition.

6. The composition according to claim 1, wherein the lubricating oil composition does not contain bright stock.

7. The composition according to claim 1, wherein the lubricating oil composition has a sulfuric acid ash content of 1.5 wt.% or more.

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

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

10. A method of thickening a lubricating oil composition in a marine diesel internal combustion engine, comprising adding to the engine the following: (a) at least 40 wt.% of an oil having a lubricating viscosity with 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 method, wherein the marine diesel lubricant composition has a TBN exceeding 30 mg KOH / g, and further, the marine diesel lubricant composition is a monograde lubricant composition satisfying the specifications of SAE J300 revised in January 2015 for SAE 30, SAE 40, SAE 50, or SAE 60 monograde lubricants.

11. The method according to claim 10, wherein the one or more olefin copolymers are present on an active substance basis at 1 to 2 wt.% of the lubricant composition.

12. The method according to claim 10, wherein the one or more olefin copolymers are the only viscosity modifier present in the lubricant composition.

13. The method according to claim 10, wherein the lubricant composition does not contain bright stock.

14. The method according to claim 10, wherein the lubricant composition has a sulfuric acid ash content of 1.5 wt.% or more.

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

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

17. A method for controlling deposit formation in an internal combustion engine, the method comprising operating the internal combustion engine with a lubricant composition comprising: (a) at least 40 wt.% of an oil having a lubricating viscosity with a kinematic viscosity at 100 °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 method, wherein the marine diesel lubricant composition has a TBN exceeding 30 mg KOH / g, and further, the marine diesel lubricant composition is a monograde lubricant composition satisfying the specifications of SAE J300 revised in January 2015 for SAE 30, SAE 40, SAE 50, or SAE 60 monograde lubricants.

18. The method according to claim 17, wherein the one or more olefin copolymers are present on an active substance basis at 1 to 2 wt.% of the lubricant composition.

19. The method according to claim 17, wherein the one or more olefin copolymers are the only viscosity modifier present in the lubricant composition.

20. The method according to claim 17, wherein the lubricant composition does not contain bright stock.

21. The method according to claim 17, wherein the lubricating oil composition has a sulfuric acid ash content of 1.5 wt.% or more.

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

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

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

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

26. The lubricating oil composition according to claim 24, which does not contain bright stock.

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