JP2005325241A - Engine oil composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine oil composition which is a phosphorus reduction-treated engine oil, but has wear resistance, heat resistance and durability equivalent to or higher that those of conventional engine oils without increasing a sulfur compound. <P>SOLUTION: This engine oil composition is characterized by containing a zinc dithiophosphate represented by the general formula (1) [R<SP>1</SP>and R<SP>2</SP>are each a hydrocarbon group; (a) is the number of 0 to 1/3] in an amount of 100 to 500 mass ppm as a phosphorus content as a component (A) and the reaction product of a divalent or more hindered alcohol with a ≥8C monocarboxylic acid in an amount of 0.01 to 20 mass % as a component (B), in a lubricating base oil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an engine oil composition for an internal combustion engine.

  The exhaust gas generated by combustion in the engine contains nitrogen oxide (NOx), sulfur oxide (SOx), particulate suspended matter (PM), and the like. These harmful substances are known to cause environmental pollution, natural destruction, adverse effects on the human body, etc., and countermeasures are required to prevent them from being released into the atmosphere as much as possible. For this reason, reduction of sulfur content and nitrogen content in fuel oil, improvement of engine, improvement of combustion method, improvement of exhaust gas purification catalyst, examination of particulate filter, and the like are being carried out.

  On the other hand, with engine oil, the wear of cams, valves, rocker arms, etc. is reduced, energy loss due to friction is reduced, thermal deterioration / oxidation deterioration of engine oil is suppressed, fuel incomplete combustion products and engine oil deterioration products in the engine Many functions such as deposition control are required. For this reason, engine oils have many additives such as anti-wear agents, friction reducers, antioxidants, ashless dispersants, metallic detergents, and viscosity index improvers added to mineral oils and synthetic oils that are base oils. It is used in the state of a blended composition. Among these additives, zinc dithiophosphate is very excellent as an antiwear agent and has excellent antioxidant properties, so that almost all engine oils actually used have a phosphorus content of 800 About 1500 mass ppm has been blended.

  A part of the engine oil enters the combustion chamber and burns, and is discharged together with the exhaust gas. It is known that the phosphorus compound in the engine oil reduces the activity of the exhaust gas purification catalyst. In addition, the sulfur content in the engine oil causes a decrease in the activity of the NOx reduction type exhaust gas purification catalyst, and adheres as a sulfate, causing clogging of the particulate filter. That is, it is preferable to reduce the phosphorus content and sulfur content in the engine oil in order to reduce harmful substances in the exhaust gas.

  Since phosphorus in engine oil is mainly derived from zinc dithiophosphate, it is necessary to reduce the zinc dithiophosphate content in order to reduce the phosphorus content. However, in phosphorus-free engine oil that does not contain zinc dithiophosphate, it is necessary to blend a large amount of a sulfur compound as an antiwear agent (see, for example, Patent Documents 1 to 5). Therefore, there has been a problem that the sulfur content in the oil increases. As engine oil with reduced phosphorus content and sulfur content, by adding zinc dithiophosphate, succinimide ashless dispersant and metal detergent, the phosphorus content is reduced to about 300-600 mass ppm. Reduced engine oils (see, for example, Patent Documents 6 and 7) are also known, but have insufficient wear resistance and antioxidant properties.

As non-metallic additives, fatty acid glycerin esters (see, for example, Patent Document 8) are well known as additives for engine oils, but the durability and heat resistance when phosphorus is reduced are insufficient. Yes, it could not be said to correspond to the reduction of the phosphorus content in engine oil.
On the other hand, ester compounds of hindered alcohols and fatty acids are well known as heat-resistant lubricating base oils (see, for example, Patent Documents 9 to 11). These are used as base oils such as diesters, triesters or full esters, and their use as additives has not been known.

JP-A-62-253691 JP-A-6-41568 JP 52-39704 A Japanese Patent Laid-Open No. 7-118680 JP 2000-63862 A JP-A-9-111275 JP 2002-53888 A JP-A-57-187394 JP-A-7-224289 Japanese Patent Laid-Open No. 9-125085 Japanese Unexamined Patent Publication No. 2000-8061

  Therefore, the problem to be solved by the present invention is that even if the engine oil has a low phosphorus prescription, the wear resistance, heat resistance and durability equal to or higher than those of the conventional engine oil can be achieved without increasing the sulfur compound. It is providing the engine oil composition which has.

Therefore, the present inventors diligently studied the engine oil with a low phosphorus prescription, and by blending an ester compound having a specific structure, it was excellent in wear resistance, heat resistance and sustainability even with a low phosphorus prescription. The present inventors have found that an engine oil can be provided and have reached the present invention.
That is, the present invention provides the lubricating base oil with the following general formula (1) as component (A):

(In the formula, R ¹ and R ² represent a hydrocarbon group, and a represents a number of 0 to 1/3.)
Zinc dithiophosphate represented by the formula: 100 to 500 ppm by mass as phosphorus content, and 0.01 to 20% by mass of a reaction product of a divalent or higher hindered alcohol and a monocarboxylic acid having 8 or more carbon atoms as the component (B). It is an engine oil composition to be contained.

The effect of the present invention is to provide an engine oil with a low phosphorus formulation that is excellent in wear resistance, heat resistance and sustainability.

First, the component (A) of the present invention will be described. The component (A) of the present invention is zinc dithiophosphate represented by the above general formula (1).
In the general formula (1), R ¹ and R ² represent a hydrocarbon group. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, and a cycloalkenyl group.

  Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, isopentyl, secondary pentyl, neopentyl, tertiary pentyl, hexyl, secondary hexyl, heptyl, 2 Secondary heptyl, octyl, 2-ethylhexyl, secondary octyl, nonyl, secondary nonyl, decyl, secondary decyl, undecyl, secondary undecyl, dodecyl, secondary dodecyl, tridecyl, isotridecyl, secondary tridecyl, tetradecyl, secondary tetradecyl , Hexadecyl, secondary hexadecyl, stearyl, eicosyl, docosyl, tetracosyl, triacontyl, 2-butyloctyl, 2-butyldecyl, 2-hexyloctyl, 2-hexyldecyl, 2-octyldecyl, 2-hexyldecyl 2-octyldodecyl, 2-decyltetradecyl, 2-dodecyl-hexadecyl, 2-hexadecyl octadecyl, 2-tetradecyl-octadecyl, monomethyl branched - include isostearyl.

Examples of the alkenyl group include vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, oleyl and the like.
As an aryl group, for example, phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, benzhydryl, trityl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, Nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, styrenated phenyl, p-cumylphenyl, phenylphenyl, benzylphenyl, α-naphthyl, β-naphthyl group and the like can be mentioned.

Examples of the cycloalkyl group and cycloalkenyl group include a cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, methylcyclohexyl, methylcycloheptyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, methylcyclopentenyl, methylcyclohexenyl, methylcycloheptenyl group. Etc.
Among these hydrocarbon groups, R ¹ and R ² are preferably an alkyl group, and more preferably a secondary alkyl group. The number of carbon atoms is preferably 3 to 14, more preferably 3 to 10, and most preferably 3 to 8. R ¹ and R ² may be the same hydrocarbon group or different hydrocarbon groups.

In general formula (1), when a = 0, it is called neutral zinc dithiophosphate (neutral salt), and when a is 1/3, it is called basic zinc dithiophosphate (basic salt). It is.
Since zinc dithiophosphate is a mixture of these neutral and basic salts, a is represented by a number from 0 to 1/3. The number of a varies depending on the production method of zinc dithiophosphate, but is preferably 0.08 to 0.3, more preferably 0.15 to 0.3, and most preferably 0.18 to 0.3. When a is larger than 0.3, the hydrolysis stability may be deteriorated. When a is smaller than 0.08, the wear resistance of the blended lubricating oil may be deteriorated.

  The content of zinc dithiophosphate represented by the general formula (1) as the component (A) with respect to the total amount of the engine oil composition of the present invention is 100 to 500 ppm by mass, preferably 150 to 480 ppm by mass, as the phosphorus content. More preferably, it is 200-470 mass ppm, Most preferably, it is 250-460 mass ppm. When the content of the component (A) is less than 100 ppm by mass as the phosphorus content, the wear resistance and the antioxidant properties are insufficient, and when it exceeds 500 ppm by mass, the activity of the exhaust gas purification catalyst tends to decrease.

Next, (B) component of this invention is demonstrated. The component (B) of the present invention is an ester compound obtained by reacting a divalent or higher hindered alcohol with a monocarboxylic acid having 8 or more carbon atoms.
Examples of the divalent or higher hindered alcohol include neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, pentaerythritol, dipentaerythritol, and dehydration condensates thereof, and mixtures thereof. It may be. Among these, neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane and pentaerythritol are preferable, and trimethylol ethane, trimethylol propane and trimethylol butane are more preferable. Any hindered alcohol having a valence of 2 or more can be used in the present invention, but it is preferably 2 to 8 valence, more preferably 2 to 6 valence, and most preferably 2 to 4 valence. In the case of monovalent hindered alcohol, the lubrication performance deteriorates, and if it exceeds 8, the product viscosity increases, the handling properties deteriorate, and the solubility in the lubricating oil also deteriorates, so the lubrication performance is insufficient. It may become.

  Examples of the monocarboxylic acid having 8 or more carbon atoms include aromatic carboxylic acids such as toluic acid, anisic acid, veratrumic acid, and piperonic acid; 2-ethylhexanoic acid, isooctanoic acid, nonanoic acid (pelargonic acid), isononanoic acid, Decanoic acid (capric acid), isodecanoic acid, undecanoic acid, isoundecanoic acid, dodecanoic acid (lauric acid), isododecanoic acid, tridecanoic acid, isotridecanoic acid, tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid ( Stearic acid), isostearic acid, eicosanoic acid (arachidic acid), docosanoic acid (behenic acid), tetracosanoic acid (lignoceric acid), hexacosanoic acid (serotic acid), octacosanoic acid (montanic acid), 10-undecenoic acid, zomarinic acid, Oleic acid, elaidic acid, linole , Linolenic acid, gadoleic acid, erucic acid, aliphatic carboxylic acids such as selacholeic acid, mixed fatty acids obtained from natural oils and fats, and mixtures thereof. Among these, from the viewpoints of solubility in lubricating base oil and lubricating performance, aliphatic monocarboxylic acids are preferable, and linear aliphatic monocarboxylic acids are more preferable. Moreover, C8-24 is preferable, C10-20 is still more preferable, and C12-18 is the most preferable. When the number of carbon atoms is less than 8, the lubricating performance does not appear. When the number of carbon atoms is more than 24, the solubility in the lubricating oil is deteriorated and the lubricating performance may be insufficient. In addition, a divalent or higher carboxylic acid is not preferable because a polymer is formed when reacted with a divalent or higher hindered alcohol and the polymer is not dissolved in the lubricating oil, and the lubricating performance becomes insufficient.

  As a method for producing the component (B), a known method can be used. Generally, it can be obtained by dehydrating condensation of a hindered alcohol and a monocarboxylic acid at 100 to 250 ° C. under reduced pressure using no catalyst or a catalyst. Catalysts that can be used include strong acids such as sulfuric acid and toluenesulfonic acid; metal halides such as titanium tetrachloride, hafnium chloride, zirconium chloride, aluminum chloride, gallium chloride, indium chloride, iron chloride, tin chloride, boron fluoride; water Sodium oxide, potassium hydroxide, cesium hydroxide, magnesium hydroxide, sodium methylate, alkali metal or alkaline earth metal hydroxide or alcoholate or carbonate such as sodium carbonate; aluminum oxide, calcium oxide, oxidation Metal oxides such as barium and sodium oxide; organometallic compounds such as tetraisopropyl titanate, dibutyltin dichloride, and dibutyltin oxide.

  The component (B) is preferably synthesized by adjusting the amount of hindered alcohol and monocarboxylic acid so as to satisfy the following mathematical formula (1).

  In general, when a polyol compound having two or more hydroxyl groups is esterified with a monocarboxylic acid, a mixture of a monoester, a diester, a triester and the like is obtained, but there is no problem as long as the general formula (1) is satisfied.

Here, the saponification value in the present invention is the number of mg of potassium hydroxide required to completely saponify 1 g of the component (B), and the hydroxyl value is obtained by acetylating 1 g of the component (B). It is the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxyl group. These analyzes can be measured by the saponification value measuring method and the hydroxyl value measuring method of JIS K0070 (Testing methods for oxidation, saponification value, ester value, iodine value, hydroxyl value and unsaponified product of chemical products). When the saponification value / (saponification value + hydroxyl value) is 0.2 or less, the component (B) may not completely dissolve in the lubricating base oil, which may cause sludge and insufficient lubrication performance. If it is greater than 0.5, the lubrication performance may be insufficient.

Component (B) used in the present invention is an appropriate amount, preferably 0.01 to 20% by mass, based on engine oil containing 100 to 500 ppm by mass of zinc dithiophosphate as component (A). Preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass is added. If the amount of component (B) added is less than 0.01% by mass, the expected effect may not be obtained. If it exceeds 20% by mass, an effect commensurate with the amount added may not be obtained, or a blended engine. The high temperature stability of the oil may deteriorate.

The lubricating base oil used in the present invention is not particularly limited, and examples thereof include general lubricating oils such as mineral oils, hydrocarbon-based synthetic oils, and mixtures thereof. More specifically, poly-α-olefin, ethylene-α-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, polyalkylene glycol, polyphenyl ether, alkyl-substituted diphenyl ether, polyol ester, dibasic acid ester, phosphoric acid Synthetic oils such as esters, phosphites, carbonates, silicone oils, and fluorinated oils, paraffinic mineral oils, naphthenic mineral oils, or refined mineral oils obtained by purifying them can be used.

Furthermore, the engine oil composition of the present invention does not refuse the addition of known lubricating oil additives, and depending on the purpose of use, an antioxidant, an organic molybdenum-based additive, an extreme pressure agent, an oiliness improver, a cleaning agent An agent, a dispersant, a viscosity index improver, a pour point depressant, a rust inhibitor, a corrosion inhibitor, an antifoaming agent, and the like may be added as long as the effects of the present invention are not impaired. However, when using phosphorus-based additives in these, the total phosphorus content in the engine oil will increase, so it should be fully considered, and if possible, use of other phosphorus-based additives Should be avoided.

Examples of the antioxidant include phenolic antioxidants and amine antioxidants. Examples of the phenolic antioxidant include 2,6-di-tert-butylphenol (hereinafter, tertiary butyl is abbreviated as t-butyl), 2,6-di-t-butyl-p-cresol, 2 , 6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4-dimethyl-6-t-butylphenol, etc., and amine-based antioxidants Examples include 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine, and phenyl-2-naphthylamine. It is done. The preferable compounding quantity of these antioxidants is 0.1-5 mass% with respect to base oil.

  Organic molybdenum additives include, for example, fatty acid molybdenum salts, sulfurized oxymolybdenum xanthate, a reaction product of molybdenum trioxide and acidic phosphate, a reaction product of molybdenum trioxide and fatty acid diethanolamide, molybdenum trioxide and glycerin monoester. Reaction product with fatty acid ester, reaction product of succinimide, carboxylic acid amide or Mannich base or their boride and molybdenum trioxide, sulfurized oxymolybdenum dithiocarbamate, sulfurized oxymolybdenum dithiophosphate, or amine and pentavalent or hexavalent Examples include a reaction product with a molybdenum compound having a molybdenum atom. The compounding quantity of these organic molybdenum type additives is 0.001-5 mass% with respect to base oil.

  Examples of extreme pressure agents include sulfur additives such as sulfurized fats and oils, olefin polysulfides, and dibenzyl sulfide; phosphorus compounds such as monooctyl phosphate, tributyl phosphate, triphenyl phosphite, tributyl phosphite, and thiophosphate An organic metal compound such as a thiophosphate metal salt, a thiocarbamic acid metal salt, and an acidic phosphate metal salt; A preferable blending amount of these extreme pressure agents is 0.1 to 10% by mass with respect to the base oil.

  Examples of the oil improver include higher alcohols such as oleyl alcohol and stearyl alcohol; fatty acids such as oleic acid and stearic acid; esters such as oleyl glycerin ester, steryl glycerin ester and lauryl glycerin ester; lauryl amide and oleyl Amides such as amide and stearylamide; amines such as laurylamine, oleylamine and stearylamine; ethers such as laurylglycerol ether and oleylglycerol ether. The preferable compounding quantity of these oiliness improvers is 0-5 mass% with respect to base oil.

  Examples of the detergent include sulfonates such as calcium, magnesium, and barium, phenates, salicylates, phosphates, and overbased salts thereof. The compounding quantity of these detergents is 0.5-10 mass% with respect to base oil.

  Examples of the dispersant include succinimides, succinic esters, benzylamines, and boron-modified products thereof to which an alkyl group or alkenyl group having a molecular weight of about 700 to 3000 is added. A preferable blending amount of these dispersants is 0.5 to 10% by mass with respect to the base oil.

  Examples of the viscosity index improver include poly (C1-18) alkyl methacrylate, (C1-18) alkyl acrylate / (C1-18) alkyl methacrylate copolymer, diethylaminoethyl methacrylate / (C1-18) alkyl methacrylate copolymer. Polymers, ethylene / (C1-18) alkyl methacrylate copolymers, polyisobutylene, polyalkylstyrene, ethylene / propylene copolymers, styrene / maleic ester copolymers, styrene / isoprene hydrogenated copolymers, and the like. . Alternatively, a dispersion type or multifunctional viscosity index improver imparted with a dispersion performance may be used. The average molecular weight is about 10,000 to 1,500,000. A preferable blending amount of these viscosity index improvers is 0.1 to 20% by mass with respect to the base oil.

  Examples of the pour point depressant include polyalkyl methacrylate, polyalkyl acrylate, polyalkyl styrene, polyvinyl acetate and the like, and the average molecular weight is 1000 to 100,000. A preferable blending amount of these pour point depressants is 0.005 to 3% by mass with respect to the base oil.

  Examples of the rust preventive include sodium nitrite, oxidized paraffin wax calcium salt, oxidized paraffin wax magnesium salt, beef tallow fatty acid alkali metal salt, alkaline earth metal salt or amine salt, alkenyl succinic acid or alkenyl succinic acid half ester (alkenyl The molecular weight of the group is about 100 to 300), sorbitan monoester, nonylphenol ethoxylate, lanolin fatty acid calcium salt and the like. The preferable compounding quantity of these rust preventives is 0.01-5 mass% with respect to base oil.

  Examples of the corrosion inhibitor include benzotriazole, benzimidazole, benzothiazole, tetraalkylthiuram disulfide and the like. The preferable compounding quantity of these corrosion inhibitors is 0.01-3 mass% with respect to base oil.

  Examples of the antifoaming agent include polydimethyl silicone, trifluoropropylmethyl silicone, colloidal silica, polyalkyl acrylate, polyalkyl methacrylate, alcohol ethoxy / propoxylate, fatty acid ethoxy / propoxylate, sorbitan partial fatty acid ester and the like. The preferable compounding quantity of these antifoaming agents is 0.001-0.1 mass% with respect to base oil.

  The engine oil composition of the present invention can be used as a lubricating oil for internal combustion engines such as gasoline engines, diesel engines, and jet engines. Among them, it can be suitably used as a lubricating oil for gasoline engines.

  Hereinafter, the engine oil composition of the present invention will be described in detail by way of examples. In the following examples,% is based on mass unless otherwise specified.

First, a mineral oil having the following properties was used as a base oil, a reference oil to which various additives were added was prepared, and the test was performed by adding the A component and the B component of the present invention thereto. The properties of the base oil and the components and blending amounts used in the test are as follows.
<Base oil>
Mineral oil based advanced VI oil. Kinematic viscosity ^{4.1mm 2 /s(100℃),18.3mm 2 / s (40} ℃), viscosity index (VI) = 126.

<Reference oil recipe>
Base oil 100 parts by weight Methacrylate viscosity index improver 3 parts by weight Succinimide dispersant 5.0 parts by weight Phenol-based antioxidant 0.3 part by weight Amine-based antioxidant 0.3 part by weight Salicylate detergent 1 .5 parts by mass

<A component>
(A-1) R ¹ = 2-octyl, zinc dithiophosphate with R ² = 2-octyl (A-2) R ¹ = n-butyl, R ² = 1-octyl zinc dithiophosphate
Phosphorus content 7.8%, a = 0.23,
Phosphorus content 8.2%, a = 0.25,

<Other additive components>
<B component>
(B-1) Trimethylolpropane oleate [0.35]
(B-2) Neopentyl glycol laurate [0.5]
(B-3) Pentaerythritol 2-ethylhexylate [0.28]
(B-4) Trimethylolpropane oleate [0.16]
(B-5) Trimethylolpropane oleate [0.6]

<Comparative product>
(C-1) Glycerin oleate [0.35]
(C-2) Oleylamide The number in [] after the component name is the value of saponification value / (saponification value + hydroxyl value).

  A predetermined amount of the component A and other additive components were added to the reference oil, and various tests were performed. Addition amounts and test results are shown in Table-1. The test method is as follows.

<Oxidation stability test of test oil>
Each additive was added to the reference oil (see Table 1) to prepare a test oil. In accordance with JIS K-2514 (Lubricant-Oxidation Stability Test Method), 250 ml of a sample is placed in a glass container containing a copper plate and an iron plate as a catalyst, and stirred at 1300 rpm while stirring air at 165.5 ° C. The test oil was oxidatively deteriorated by heating at 168 hours. Kinematic viscosity (40 ° C.) was measured for the test oil before and after the deterioration test. The results show that the smaller the viscosity ratio (the value obtained by dividing the deteriorated kinematic viscosity by the kinematic viscosity before deterioration), the higher the oxidation stability.

<Lubrication performance test>
Using the lubricating composition (new oil) of the product of the present invention and the comparative product and its deteriorated oil, the average was obtained under the conditions of a load of 30 kg, room temperature, number of revolutions of 1,500 rpm, and time of 10 minutes using a shell type high-speed four-ball tester. The coefficient of friction and the wear scar diameter of the ball were measured. The average coefficient of friction was measured with a new oil, and the test oil after the above oxidation stability test was used as the deteriorated oil for measuring the wear scar after the deterioration.

As shown in Table 1, in all examples, the wear scar and the average friction coefficient were small, and the viscosity ratio before and after deterioration was small as compared with the comparative example. From this, it was confirmed that the component (B) of the present invention exerts an effect on the engine oil having a low phosphorus prescription.

Claims (5)

In the lubricating base oil, as the component (A), the following general formula (1):

(In the formula, R ¹ and R ² represent a hydrocarbon group, and a represents a number of 0 to 1/3.)
Zinc dithiophosphate represented by the formula: 100 to 500 ppm by mass as phosphorus content, and 0.01 to 20% by mass of a reaction product of a divalent or higher hindered alcohol and a monocarboxylic acid having 8 or more carbon atoms as the component (B). Contains engine oil composition. The engine oil composition according to claim 1, wherein the component (B) has a characteristic represented by the following mathematical formula (1).

  The engine oil composition according to claim 1 or 2, wherein the (B) component monocarboxylic acid is a fatty acid having 8 to 24 carbon atoms.   The engine oil composition according to any one of claims 1 to 3, wherein the hindered alcohol is trimethylolpropane, pentaerythritol, or neopentyl glycol.   Select from the group consisting of antioxidants, organic molybdenum additives, extreme pressure agents, oiliness improvers, detergents, dispersants, viscosity index improvers, pour point depressants, rust inhibitors, corrosion inhibitors and antifoaming agents The engine oil composition according to any one of claims 1 to 4, further comprising one kind or two or more kinds.