JP2013224404A - Lubricating oil composition for engine made of aluminum alloy and lubrication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a lubricating oil composition for an engine made of an aluminum alloy in which abrasion resistance to a sliding part is excellent in the engine in which the sliding part is the aluminum alloy, and that can greatly decrease ZnDTP and a metal based detergent containing phosphorus voluminously while maintaining the abrasion resistance to the aluminum alloy; and a lubrication method using the same.SOLUTION: A lubricating oil composition comprises a base oil, a succinimide compound and a sulfur-containing heterocyclic compound represented by general formula (I), and has a sulfur content of 0.10 to 1.00 mass% relative to the composition and a phosphorus content of 0.03 to 0.06 mass% and a sulfated ash content of less that 0.3 mass% relative to the composition. In the formula, As is a sulfur-containing heterocycle; R1 and R2 are each independently hydrogen, amino, 1-50C hydrocarbon which is selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl and aryl, or a 1-50C hetero atom-containing group that includes an atom selected from oxygen, nitrogen and sulfur when they are the hydrocarbon group; and k, l, m and n are each independently an integer of 0 to 5.

Description

  The present invention relates to an aluminum alloy engine lubricating oil composition and a lubricating method using the same. More particularly, the present invention relates to an aluminum alloy engine lubricating oil composition and a lubricating method that are particularly useful for internal combustion engines such as gasoline engines, diesel engines, and gas engines.

In recent years, strict regulations on exhaust gas have been introduced one after another in the automobile industry for the purpose of reducing environmental load, and exhaust gas aftertreatment devices have been developed. In addition to carbon dioxide (CO ₂ ), which is a global warming substance, exhaust gases include particulate substances (PM), hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx), which are harmful substances. ) And the like, and the regulation values for PM and NOx are extremely strict. As measures to reduce these emissions, gasoline vehicles are equipped with a three-way catalyst, and diesel vehicles are equipped with a diesel particulate filter (DPF). As a result, the exhaust gas is cleaned and released into the atmosphere.
On the other hand, it has been reported that the phosphorus content in engine oil poisons the active sites of the three-way catalyst and lowers the catalytic function, and the ash content derived from metal components accumulates in the DPF to shorten the life. Currently, upper limits of phosphorus and ash are established in the ILSAC standards and JASO standards, which are engine oil standards, and development of engine oils with reduced amounts of these is being promoted.

In recent years, from the viewpoint of improving fuel consumption, weight reduction has been promoted by non-ferrous engines and transmission parts. Of these, aluminum alloys, particularly Al-Si alloys, are often used, but as an anti-wear agent, an additive for forming a film on Fe such as zinc dithiophosphate (ZnDTP) is used. For this reason, there is a concern that the wear resistance of aluminum materials such as Al-Si alloys may be reduced.
Therefore, research on a good antiwear agent for aluminum materials has been conducted (for example, see Patent Document 1).

Special table 2010-528155

  However, none of these conventional antiwear agents can achieve a sufficient effect unless combined with ZnDTP containing a large amount of phosphorus, and the adverse effects on the exhaust gas aftertreatment device are not wiped away. Was in the situation. Therefore, even if the phosphorus content is further reduced or no phosphorus content is contained, the appearance of an engine lubricating oil composition having excellent wear resistance with respect to an aluminum material has been desired.

  Under such circumstances, the present invention provides an engine lubricating oil composition made of an aluminum alloy having excellent wear resistance against the sliding portion in an engine having a sliding portion made of an aluminum alloy. An object of the present invention is to provide an aluminum alloy engine lubricating oil composition capable of greatly reducing ZnDTP and metal detergents containing a large amount of phosphorus while maintaining the properties, and a lubricating method using the same. Is.

As a result of intensive studies, the present inventors have found that the above object can be achieved by using a succinimide compound and a specific sulfur-containing heterocyclic compound in combination. The present invention has been completed based on such findings.
That is, the present invention
[1] A base oil, a succinimide compound, and a sulfur-containing heterocyclic compound represented by the following general formula (I):
The sulfur content based on the total amount of the composition is 0.10% by mass to 1.00% by mass, the phosphorus content based on the total amount of the composition is 0.03% by mass to 0.06% by mass, and sulfuric acid An aluminum alloy engine lubricating oil composition having an ash content of less than 0.3% by mass;

(In the formula, As is a sulfur-containing heterocyclic ring, R ¹ and R ² are each independently a hydrogen atom; an amino group; an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, and an aryl group. Or a hydrocarbon group having 50 to 50 carbon atoms; or a hydrocarbon group having 1 to 50 carbon atoms containing an atom selected from an oxygen atom, a nitrogen atom and a sulfur atom in the hydrocarbon group. , L, m and n are each independently an integer of 0 or more and 5 or less.)
[2] The lubricating oil composition for an aluminum alloy engine according to [1], wherein the nitrogen content derived from the succinimide compound is 0.08% by mass or more and 0.40% by mass or less based on the total amount of the composition,
[3] The aluminum alloy engine lubricating oil composition according to [2], wherein the succinimide compound includes a boron derivative thereof,
[4] In the general formula (I), both m and n are not 0. [1] The lubricating oil composition for engines according to any one of [1] to [3],
[5] The lubricating oil composition for an engine made of aluminum alloy according to any one of [1] to [4], wherein in the general formula (I), the sulfur-containing heterocycle is a thiadiazole ring,
[6] The aluminum alloy engine according to [5], wherein the thiadiazole ring is a 1,3,4-thiadiazole ring, and a sulfur atom is bonded to positions 2 and 5 of the 1,3,4-thiadiazole ring. Lubricating oil composition,
[7] The lubricating oil composition for an engine made of aluminum alloy according to [6], wherein one sulfur atom is bonded to each of positions 2 and 5 of the 1,3,4-thiadiazole ring.
[8] An engine having a sliding part made of an aluminum alloy, wherein the lubricating oil composition for an engine according to any one of [1] to [7] is used for the sliding part. Lubrication method for alloy engine,
Is to provide.

  According to the present invention, in an engine having a sliding part made of an aluminum alloy, an aluminum alloy engine lubricating oil composition having excellent wear resistance against the sliding part, while maintaining the wear resistance against the aluminum alloy. An aluminum alloy engine lubricating oil composition capable of greatly reducing ZnDTP and metal detergent containing a large amount of phosphorus and a lubricating method using the same are provided.

  The aluminum alloy engine lubricating oil composition of the present invention (hereinafter sometimes simply referred to as “lubricating oil composition”) is represented by a base oil, a succinimide compound, and the following general formula (I): A sulfur-containing heterocyclic compound, the sulfur content on the basis of the total composition is 0.10% by mass or more and 1.00% by mass or less, and the phosphorus content on the basis of the total amount of the composition is 0.03% by mass or more. It is 0.06 mass% or less, and the amount of sulfated ash is less than 0.3 mass%.

In the above formula, As is a sulfur-containing heterocycle, R ¹ and R ² are each independently a hydrogen atom, an amino group, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, and an aryl group. A hydrocarbon group having 50 to 50 carbon atoms; or, when these are hydrocarbon groups, a C 1-50 heteroatom-containing group containing an atom selected from an oxygen atom, a nitrogen atom and a sulfur atom in the hydrocarbon group. k, l, m, and n are each independently an integer of 0 or more and 5 or less.

Hereafter, each said requirement is demonstrated.
[Base oil]
There is no restriction | limiting in particular as base oil used in this invention, Arbitrary things can be suitably selected and used from the mineral oil and synthetic oil conventionally used as base oil of lubricating oil.
As the mineral oil, for example, a lubricating oil fraction obtained by distillation under reduced pressure of atmospheric residual oil obtained by atmospheric distillation of crude oil, solvent removal, solvent extraction, hydrocracking, solvent dewaxing, contact Mineral oil refined by carrying out one or more treatments such as dewaxing, hydrorefining, etc., or mineral oil produced by isomerizing wax, GTL WAX, and the like.

On the other hand, examples of the synthetic oil include polybutene, polyolefin [α-olefin homopolymer and copolymer (eg, ethylene-α-olefin copolymer)], and various esters (eg, polyol ester, dibasic acid). Ester, phosphate ester, etc.), various ethers (eg, polyphenyl ether), polyglycol, alkylbenzene, alkylnaphthalene and the like. Of these synthetic oils, polyolefins and polyol esters are particularly preferable.
In this invention, the said mineral oil may be used individually by 1 type as a base oil, and may be used in combination of 2 or more type. Moreover, the said synthetic oil may be used 1 type and may be used in combination of 2 or more type. Further, one or more mineral oils and one or more synthetic oils may be used in combination.

No particular limitation is imposed on the viscosity of the base oil, kinematic viscosity at 100 ° C. of preferably not more than 1.5 mm ² / s or more 50 mm ² / s, more preferably 3 mm ² / s or more 30 mm ² / s or less , more preferably not more than 3 mm ² / s or more 15 mm ² / s.
When the kinematic viscosity at 100 ° C. is 1.5 mm ² / s or more, the evaporation loss is small, and when it is 50 mm ² / s or less, the power loss due to the viscous resistance is suppressed, and the fuel efficiency improvement effect is obtained.

As the base oil,% by ring analysis C _A content of sulfur is preferably used include: 50 ppm by mass 3.0. Here, the% C _A by ring analysis shows a proportion of aromatic content calculated by ring analysis n-d-M method (percentage). The sulfur content is a value measured according to JIS K2541.
_A base oil having a% CA of 3.0 or less and a sulfur content of 50 mass ppm or less provides a lubricating oil composition having good oxidation stability and capable of suppressing an increase in acid value and sludge formation. be able to. A more preferable% C _A is 1.0 or less, further 0.5 or less, and a more preferable sulfur content is 30 mass ppm or less.

  Furthermore, the viscosity index of the base oil is preferably 70 or more, more preferably 90 or more, and still more preferably 100 or more. The base oil having a viscosity index of 70 or more has a small change in viscosity due to a change in temperature.

[Succinimide compound]
Examples of the succinimide compound in the present invention include a monotype succinimide compound represented by the following general formula (II) or a bis type succinimide compound represented by the following general formula (III). It is done.

In the above general formulas (II) and (III), R ³ , R ⁵ and R ⁸ are each an alkenyl group or alkyl group having a number average molecular weight of 500 to 4,000, and R ⁵ and R ⁸ are the same or different. It may be. The number average molecular weight of R ³ , R ⁵ and R ⁸ is preferably 1,000 or more and 4,000 or less.
If the number average molecular weight of R ³ , R ⁵ and R ⁸ is 500 or more, the solubility in the base oil is good, and if it is 4,000 or less, the dispersibility does not deteriorate.

R ⁴ , R ⁶ and R ⁷ are each an alkylene group having 2 to 5 carbon atoms, R ⁶ and R ⁷ may be the same or different, r is an integer of 1 to 10, and s Represents an integer of 0 or 1 to 10. The r is preferably 2 or more and 5 or less, more preferably 3 or more and 4 or less. When r is 1 or more, the dispersibility is good, and when r is 10 or less, the solubility in the base oil is also good.
Further, in the general formula (III), s is preferably 1 or more and 4 or less, more preferably 2 or more and 3 or less. If s is in the above range, it is preferable in view of dispersibility and solubility in base oil.

Examples of the alkenyl group include a polybutenyl group, a polyisobutenyl group, and an ethylene-propylene copolymer, and the alkyl group is a hydrogenated form thereof. Representative examples of suitable alkenyl groups include polybutenyl or polyisobutenyl groups. The polybutenyl group can be obtained by polymerizing a mixture of 1-butene and isobutene or high-purity isobutene. A representative example of a suitable alkyl group is a hydrogenated polybutenyl group or polyisobutenyl group.
As the succinimide compound, an alkenyl succinimide compound such as polybutenyl succinimide or an alkyl succinimide compound is preferably used.

  The alkenyl succinimide compound or the alkyl succinimide compound is generally an alkenyl succinic anhydride obtained by reaction of polyolefin and maleic anhydride, or an alkyl succinic anhydride obtained by hydrogenating it, and a polyamine. It can manufacture by making it react. The mono-type succinimide compound and the bis-type succinimide compound can be produced by changing the reaction ratio of the alkenyl succinic anhydride or alkyl succinic anhydride and polyamine.

As the olefin monomer forming the polyolefin, one or two or more kinds of α-olefins having 2 to 8 carbon atoms can be mixed and used, and a mixture of isobutene and 1-butene is preferably used. Can do.
Examples of the polyamine include single diamines such as ethylenediamine, propylenediamine, butylenediamine, and pentylenediamine; diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di (methylethylene) triamine, dibutylenetriamine, And polyalkylene polyamines such as tributylenetetramine and pentapentylenehexamine; piperazine derivatives such as aminoethylpiperazine; and the like.

Further, as the succinimide compound, in addition to the alkenyl or alkyl succinimide compound, a boron derivative thereof and / or a compound obtained by modifying these with an organic acid may be used.
As the boron derivative of the alkenyl or alkyl succinimide compound, those produced by a conventional method can be used. For example, after reacting the polyolefin with maleic anhydride to make an alkenyl succinic anhydride, the above polyamine and boron oxide, boron halide, boric acid, boric anhydride, boric acid ester, ammonium salt of boric acid It can be obtained by reacting with an intermediate obtained by reacting a boron compound such as, and imidizing.
Although there is no restriction | limiting in particular in boron content in this boron derivative, As boron, it is 0.05 mass% or more and 5 mass% or less normally, Preferably it is 0.1 mass% or more and 3 mass% or less.

  Moreover, it is preferable that the compounding quantity of the said succinimide compound is 0.08 mass% or more and 0.40 mass% or less on the basis of lubricating oil composition whole quantity as nitrogen content derived from this succinimide compound. When the nitrogen content is in the above range, the high temperature cleanliness of the lubricating oil composition is sufficiently improved, and the low temperature fluidity is also greatly improved. The nitrogen content is more preferably 0.08% by mass or more and 0.35% by mass or less.

Furthermore, when the succinimide compound contains the boron derivative, the boron content derived from the boron derivative is preferably 0.020% by mass or more and 0.3% by mass or less based on the total amount of the composition. When the boron content is within this range, good cleanability and dispersibility can be obtained. The boron content is more preferably 0.025% by mass or more and 0.25% by mass or less.
In this case, the mass ratio (B / N) of the boron content to the nitrogen content is preferably 0.07 or more and 1.0 or less, and more preferably 0.09 or more and 0.95 or less. preferable.

[Sulfur-containing heterocyclic compounds]
The sulfur-containing heterocyclic compound in the present invention is represented by the following general formula (I).

In the above formula, As is a sulfur-containing heterocyclic ring, R ¹ and R ² are each independently a hydrogen atom; an amino group; an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, and an aryl group. A hydrocarbon group having 50 to 50 carbon atoms; or, when these are hydrocarbon groups, a C 1-50 heteroatom-containing group containing an atom selected from an oxygen atom, a nitrogen atom and a sulfur atom in the hydrocarbon group. k, l, m, and n are each independently an integer of 0 or more and 5 or less.
In the general formula (I), m and n are not both 0, that is, at least one sulfur atom is bonded to at least one side of the sulfur-containing heterocyclic ring, from the viewpoint of improving wear resistance. To preferred. Furthermore, it is more preferable that this sulfur atom is bonded to both sides of the sulfur-containing heterocyclic ring.

Examples of the sulfur-containing heterocycle include, for example, each substituted or unsubstituted benzothiophene ring, naphthothiophene ring, dibenzothiophene ring, thienothiophene ring, dithienobenzene ring, thiazole ring, thiophene ring, thiazoline ring, and benzothiazole ring. , Naphthothiazole ring, isothiazole ring, benzoisothiazole ring, naphthisothiazole ring, thiadiazole ring, phenothiazine ring, phenoxathiin ring, dithiaphthalene ring, thianthrene ring, thioxanthene ring, bithiophene ring, etc. .
Among these, a thiadiazole ring is preferably used from the viewpoint of improving wear resistance.

The thiadiazole ring is more preferably a 1,3,4-thiadiazole ring. Furthermore, the sulfur-containing heterocyclic compound in the present invention is a sulfur atom at the 2,5 position of the 1,3,4-thiadiazole ring. It is more preferable from the viewpoint of improving the wear resistance.
Furthermore, it is particularly preferable from the viewpoint of improving abrasion resistance that the structure includes one sulfur atom bonded to each of the 2,5th and 5th positions of the 1,3,4-thiadiazole ring.

In the general formula (I), the alkyl group represented by R ¹ and R ² is preferably an alkyl group having 1 to 30 carbon atoms, and more preferably an alkyl group having 1 to 24 carbon atoms. Specific examples of the alkyl group include, for example, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various hexyl groups, various octyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups. And various octadecyl groups and various icosyl groups. The alkyl group may be substituted with an aromatic group, and examples thereof include a benzyl group and a phenethyl group.
The cycloalkyl group represented by R ¹ and R ² is preferably a cycloalkyl group having 3 to 30 carbon atoms, and more preferably a cycloalkyl group having 3 to 24 carbon atoms. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a methylcyclopentyl group, a dimethylcyclopentyl group, a methylethylcyclopentyl group, a diethylcyclopentyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, and a methylethylcyclohexyl group. And a diethylcyclohexyl group. Moreover, the cycloalkyl group may be substituted with an aromatic group, and examples thereof include a phenylcyclopentyl group and a phenylcyclohexyl group.
The alkenyl group represented by R ¹ and R ² is preferably an alkenyl group having 2 to 30 carbon atoms, and more preferably an alkenyl group having 2 to 24 carbon atoms. Specific examples of the alkenyl group include, for example, vinyl group, allyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-methylvinyl group, 1-methylallyl group, 1,1-dimethylallyl group, 2 -A methylallyl group, a nonenyl group, a decenyl group, an octadecenyl group, etc. are mentioned. The alkenyl group may be substituted with an aromatic group.
The cycloalkenyl group represented by R ¹ and R ² is preferably a cycloalkenyl group having 3 to 30 carbon atoms, and more preferably a cycloalkenyl group having 3 to 24 carbon atoms. Specific examples of the cycloalkenyl group include a cyclobutenyl group and a methylcyclobutenyl group. The cycloalkenyl group may be substituted with an aromatic group.
The aryl group represented by R ¹ and R ² is preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 24 carbon atoms. Specific examples of the aryl group include phenyl group, tolyl group, xylyl group, naphthyl group, butylphenyl group, octylphenyl group, nonylphenyl group and the like.

  Examples of the sulfur-containing heterocyclic compound represented by the general formula (I) include compounds represented by the following formulas.

  In addition to the above, examples of the sulfur-containing heterocyclic compound represented by the general formula (I) include 2- (2-ethylhexylthio) thiazole, 2,4-bis (2-ethylhexylthio) thiazole, 2,5 -Bis (t-norylthio) -1,3,4-thiadiazole, 2,5-bis (dimethylhexylthio) -1,3,4-thiadiazole, 2,5-bis (octadecenylthio) -1,3 , 4-thiadiazole, 2,5-bis (methylhexadecenylthio) -1,3,4-thiadiazole, 2-octylthio-thiazoline, 2- (2-ethylhexylthio) benzothiazole, 2- (2-ethylhexylthio) ) Thiophene, 2,4-bis (2-ethylhexylthio) thiophene, 2- (2-ethylhexylthio) thiazoline, 2,5-bis (2-hydroxy) Octadecylthio) -1,3,4-thiadiazole, 2,5-bis (n-octoxycarbonylmethylthio) -1,3,4-thiadiazole, 2-mercapto-5- (2-ethylhexylthio) -1,3 , 4-thiadiazole, 2-mercapto-5- (t-norylthio) -1,3,4-thiadiazole,

  2- (2-ethylhexyldithio) thiazole, 2,4-bis (2-ethylhexyldithio) thiazole, 2,5-bis (t-noryldithio) -1,3,4-thiadiazole, 2,5-bis (dimethylhexyl) Dithio) -1,3,4-thiadiazole, 2,5-bis (octadecenyldithio) -1,3,4-thiadiazole, 2,5-bis (methylhexadecenyldithio) -1,3 4-thiadiazole, 2-octyldithio-thiazoline, 2- (2-ethylhexyldithio) benzothiazole, 2- (2-ethylhexyldithio) thiophene, 2,4-bis (2-ethylhexyldithio) thiophene, 2- (2- Ethylhexyldithio) thiazoline, 2,5-bis (2-hydroxyoctadecyldithio) -1,3,4-thiadiazole, 2 5-bis (n-octoxycarbonylmethyldithio) -1,3,4-thiadiazole, 2-mercapto-5- (2-ethylhexyldithio) -1,3,4-thiadiazole, 2-mercapto-5- (t -Noryldithio) -1,3,4-thiadiazole,

  2- (2-ethylhexylamino) thiazole, 2,4-bis (2-ethylhexylamino) thiazole, 2,5-bis (t-norylamino) -1,3,4-thiadiazole, 2,5-bis (dimethylhexyl) Amino) -1,3,4-thiadiazole, 2,5-bis (octadecenylamino) -1,3,4-thiadiazole, 2,5-bis (methylhexadecenylamino) -1,3 4-thiadiazole, 2-octylamino-thiazoline, 2- (2-ethylhexylamino) benzothiazole, 2- (2-ethylhexylamino) thiophene, 2,4-bis (2-ethylhexylamino) thiophene, 2- (2- Ethylhexylamino) thiazoline, 2,5-bis (2-hydroxyoctadecylamino) -1,3,4-thiadiazole, 2 5-bis (n-octoxycarbonylmethylamino) -1,3,4-thiadiazole, 2-amino-5- (2-ethylhexylamino) -1,3,4-thiadiazole, 2-amino-5- (t -Norylamino) -1,3,4-thiadiazole,

  2- (2-ethylhexyl) thiazole, 2,4-bis (2-ethylhexyl) thiazole, 2,5-bis (t-noryl) -1,3,4-thiadiazole, 2,5-bis (dimethylhexyl)- 1,3,4-thiadiazole, 2,5-bis (octadecenyl) -1,3,4-thiadiazole, 2,5-bis (methylhexadecenyl) -1,3,4-thiadiazole, 2-octyl- Thiazoline, 2- (2-ethylhexyl) benzothiazole, 2- (2-ethylhexyl) thiophene, 2,4-bis (2-ethylhexyl) thiophene, 2- (2-ethylhexyl) thiazoline, 2,5-bis (2- Hydroxyoctadecyl) -1,3,4-thiadiazole, 2,5-bis (n-octoxycarbonylmethyl) -1,3,4-thiadiazole 2- (2-ethylhexyl) -1,3,4-thiadiazole, 2- (t-Noryl) such as 1,3,4-thiadiazole and the like.

  In the lubricating oil composition of the present invention, the sulfur content is 0.10% by mass or more and 1.00% by mass or less based on the total amount of the composition. If the sulfur content is less than 0.10% by mass, sufficient wear resistance cannot be obtained, and if it exceeds 1.00% by mass, corrosion may occur. The sulfur content is preferably 0.12% by mass or more and 0.90% by mass or less, more preferably 0.15% by mass or more and 0.85% by mass or less based on the total amount of the composition.

In the lubricating oil composition of the present invention, the phosphorus content is 0.03% by mass or more and 0.06% by mass or less based on the total amount of the composition. If the phosphorus content in the composition is 0.03% by mass or more, the wear resistance required as engine lubricating oil is further enhanced, and if it is 0.06% by mass or less, a three-way catalyst The poisoning action of the active sites is suppressed, and the catalyst life can be extended. Accordingly, the phosphorus content is preferably 0.03% by mass or more and 0.055% by mass or less, and more preferably 0.03% by mass or more and 0.050% by mass or less.
What is necessary is just to adjust phosphorus content with the compounding quantity of a phosphorus-type antiwear agent. Examples of typical phosphorus antiwear agents include phosphate ester and thiophosphate esters, but phosphites, alkyl hydrogen phosphites, phosphate ester amine salts, etc. are preferred. In particular, zinc dithiophosphate (ZnDTP) is preferred.

  On the other hand, in the lubricating oil composition of the present invention, the sulfated ash content is less than 0.3% by mass. If the amount of sulfated ash content in the composition is less than 0.3% by mass, the ash content derived from the metal component is suppressed from being deposited on the DPF, and the lifetime can be extended. Accordingly, the sulfated ash content in the composition is preferably 0.25% by mass or less, more preferably 0.20% by mass or less, and particularly preferably 0.15% by mass or less.

  In the lubricating oil composition of the present invention, conventionally known additives may be blended within a range that does not impair the effect. Examples of the additive include an antioxidant, a metallic detergent, a viscosity index improver, a pour point depressant, a metal deactivator, a rust inhibitor, and an antifoaming agent.

As said antioxidant, the antioxidant which does not contain phosphorus is preferable, for example, a phenolic antioxidant, an amine antioxidant, a molybdenum amine complex antioxidant, a sulfur type antioxidant, etc. are mentioned.
Examples of phenolic antioxidants include 4,4′-methylenebis (2,6-di-t-butylphenol), 4,4′-bis (2,6-di-t-butylphenol), and 4,4 ′. -Bis (2-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-methyl-6) -Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol); 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,6-di-t-butyl -4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-amyl-p-cresol, 2,6 -Di-t-butyl-4- (N, N'-dimethylaminomethylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl- 6-t-butylphenol), 2,2′-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5- Di-t-butyl-4-hydroxybenzyl) sulfide, n-octyl-3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, n-octadecyl-3- (4-hydroxy-3, 5-di-t-butylphenyl) propionate, 2,2′-thio [diethyl-bis-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] and the like.
Among these, bisphenol-based and ester group-containing phenol-based ones are particularly preferable.

Examples of the amine antioxidant include monoalkyl diphenylamines such as monooctyl diphenylamine and monononyl diphenylamine; 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, and 4,4′-dihexyldiphenylamine. 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, dialkyldiphenylamines such as 4,4'-dinonyldiphenylamine; tetrabutyldiphenylamine, tetrahexyldiphenylamine; polyoctyldiphenylamine, tetranonyldiphenylamine Alkyldiphenylamine system; and α-naphthylamine, phenyl-α-naphthylamine, and further butylphenyl-α-naphthylamine, pentylphenyl-α- Fuchiruamin, hexylphenyl -α- naphthylamine, heptylphenyl -α- naphthylamine, octylphenyl -α- naphthylamine, alkylated phenyl -α- naphthylamine, such as nonylphenyl -α- naphthylamine; and the like.
Of these, those of dialkyldiphenylamine type and naphthylamine type are preferred.

Examples of the molybdenum amine complex-based antioxidant include hexavalent molybdenum compounds, specifically, those obtained by reacting molybdenum trioxide and / or molybdic acid with an amine compound, for example, JP-A-2003-252887. A compound obtained by the described production method can be used.
Although it does not restrict | limit especially as an amine compound made to react with the said hexavalent molybdenum compound, Specifically, a monoamine, diamine, a polyamine, and an alkanolamine are mentioned. More specifically, it has an alkyl group having 1 to 30 carbon atoms such as methylamine, ethylamine, dimethylamine, diethylamine, methylethylamine, and methylpropylamine (these alkyl groups may be linear or branched). Alkylamines; alkenylamines having 2 to 30 carbon atoms such as ethenylamine, propenylamine, butenylamine, octenylamine, and oleylamine (these alkenyl groups may be linear or branched); methanolamine, ethanolamine Alkanolamines having 1-30 carbon atoms such as methanolethanolamine, methanolpropanolamine, etc. (these alkanol groups may be linear or branched); methylenediamine, ethylenediamine, propylene diene And alkylenediamines having 1-30 carbon atoms such as butylenediamine; polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine; undecyldiethylamine, undecyldiethanolamine, dodecyldipropanolamine , Oleyldiethanolamine, oleylpropylenediamine, stearyltetraethylenepentamine and other monoamines, diamines, polyamines having a C8-20 alkyl group or alkenyl group, and heterocyclic compounds such as imidazoline; alkylene oxides of these compounds And adducts; and mixtures thereof.
Moreover, the sulfur containing molybdenum complex etc. of the succinimide described in Japanese Patent Publication No. 3-22438 and Unexamined-Japanese-Patent No. 2004-2866 can be illustrated, and specifically, the following processes (m) and (n) Can be manufactured.
(M) an acidic molybdenum compound or a salt thereof, succinimide, carboxylic acid amide, hydrocarbon monoamine, hydrocarbon polyamine, Mannich base, phosphonic acid amide, thiophosphonic acid amide, phosphoric acid amide, dispersant-type viscosity index improver, and A step of forming a molybdenum complex by reacting a basic nitrogen compound selected from the group consisting of these mixtures with a reaction temperature maintained at about 120 ° C. or lower.
(N) The product of step (m) is subjected to at least one stripping or sulfiding step or both steps. However, when the molybdenum complex is diluted with isooctane and measured in a quartz cell having an optical path length of 1 centimeter with a UV-visible spectrophotometer at a constant molybdenum concentration of 0.00025 g of molybdenum per gram of diluted molybdenum complex, a wavelength of 350 Taking sufficient time to give a molybdenum complex having an absorbance at the nanometer of less than 0.7, and maintaining the temperature of the reaction mixture in the stripping or sulfiding step below about 120 ° C.
The molybdenum complex can also be produced by the following steps (o), (p) and (q).
(O) acidic molybdenum compound or salt thereof, succinimide, carboxylic acid amide, hydrocarbon monoamine, hydrocarbon polyamine, Mannich base, phosphonic acid amide, thiophosphonic acid amide, phosphoric acid amide, dispersant-type viscosity index improver, and A step of forming a molybdenum complex by reacting a basic nitrogen compound selected from the group consisting of these mixtures with a reaction temperature maintained at about 120 ° C. or lower.
(P) stripping the product of step (o) at a temperature of about 120 ° C. or less.
(Q) The resulting product is at a temperature of about 120 ° C. or less, the molar ratio of sulfur to molybdenum is about 1: 1 or less, and the molybdenum complex diluted with isooctane is diluted with 0 molybdenum / g molybdenum complex. Sufficient to give a molybdenum complex with an absorbance at less than 0.7 at a wavelength of 350 nanometers when measured in a quartz cell with an optical path length of 1 centimeter with a UV-visible spectrophotometer at a constant molybdenum concentration of .00025 g. The process of sulfiding over time.

  Examples of the sulfur-based antioxidant include phenothiazine, pentaerythritol-tetrakis- (3-laurylthiopropionate), didodecyl sulfide, dioctadecyl sulfide, didodecylthiodipropionate, dioctadecylthiodipropionate, Examples include myristyl thiodipropionate, dodecyl octadecyl thiodipropionate, and 2-mercaptobenzimidazole.

Among such antioxidants, phenol-based antioxidants and amine-based antioxidants are preferable from the viewpoint of reducing metal content and sulfur content. Moreover, the said antioxidant may be used individually by 1 type, and 2 or more types may be mixed and used for it. Among these, from the viewpoint of the effect of oxidation stability, a mixture of one or more phenolic antioxidants and one or more amine antioxidants is preferable.
The blending amount of the antioxidant is usually preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, based on the total amount of the composition. The amount of the molybdenum complex is preferably 10 to 1000 ppm by mass, more preferably 30 to 800 ppm by mass, more preferably 50 to 500 ppm by mass in terms of molybdenum based on the total amount of the composition. Is more preferable.

  As the metal detergent, any alkaline earth metal detergent used for lubricating oil can be used, for example, alkaline earth metal sulfonate, alkaline earth metal phenate, alkaline earth metal salicylate, and these. Examples thereof include a mixture of two or more selected from the inside.

  The alkaline earth metal sulfonate is an alkaline earth metal salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a molecular weight of 300 to 1,500, preferably 400 to 700, particularly magnesium. Examples thereof include salts and / or calcium salts, among which calcium salts are preferably used.

  Examples of the alkaline earth metal phenates include alkylphenols, alkylphenol sulfides, alkaline earth metal salts of Mannich reaction products of alkylphenols, particularly magnesium salts and / or calcium salts, among which calcium salts are particularly preferably used.

  Examples of the alkaline earth metal salicylate include alkaline earth metal salts of alkyl salicylic acid, particularly magnesium salts and / or calcium salts, among which calcium salts are preferably used.

The alkyl group constituting the alkaline earth metal detergent is preferably an alkyl group having 4 to 30 carbon atoms, more preferably an alkyl group having 6 to 18 carbon atoms, which may be linear or branched.
These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

  Further, as the alkaline earth metal sulfonate, alkaline earth metal phenate and alkaline earth metal salicylate, the above-mentioned alkyl aromatic sulfonic acid, alkylphenol, alkylphenol sulfide, Mannich reaction product of alkylphenol, alkylsalicylic acid, etc. are directly added to magnesium and / or Or it reacts with alkaline earth metal bases such as calcium alkaline earth metal oxides and hydroxides, or once is converted to an alkali metal salt such as sodium salt or potassium salt and then substituted with alkaline earth metal salt, etc. Neutral alkaline earth metal sulfonates, neutral alkaline earth metal phenates and neutral alkaline earth metal salicylates obtained as well as neutral alkaline earth metal sulfonates, neutral alkaline earth metal phenates and neutral alkaline earths Basic alkaline earth metal sulfonate, basic alkaline earth metal phenate and basic alkaline earth metal obtained by heating metal salicylate and excess alkaline earth metal salt or alkaline earth metal base in the presence of water Obtained by reacting salicylates or neutral alkaline earth metal sulfonates, neutral alkaline earth metal phenates and neutral alkaline earth metal salicylates in the presence of carbon dioxide with alkaline earth metal carbonates or borates. Also included are overbased alkaline earth metal sulfonates, overbased alkaline earth metal phenates and overbased alkaline earth metal salicylates.

  The metal detergent used in the present invention is preferably an alkaline earth metal salicylate or alkaline earth metal phenate for the purpose of reducing the sulfur content in the composition, and more preferably an overbased salicylate or an overbased phenate, In particular, overbased calcium salicylate is preferred.

The total base number of the metal detergent used in the present invention is preferably 10 mgKOH / g or more and 500 mgKOH / g or less, more preferably 15 mgKOH / g or more and 450 mgKOH / g or less, one or two or more selected from these Can be used together.
The total base number referred to here is JIS K 2501 “Petroleum products and lubricants—Test method for neutralization number”. Means the total base number by potentiometric titration method (base number / perchloric acid method) measured according to the above.

Further, the metal detergent used in the present invention is not particularly limited in its metal ratio, and usually 20 or less can be used singly or in combination of two or more, but preferably the metal ratio is 3 or less. It is particularly preferable to use a metal detergent having a viscosity of 1.5 or less, particularly preferably 1.2 or less, because it is excellent in oxidation stability, base number maintenance, high-temperature cleanability and the like.
The metal ratio here is expressed by the valence of the metal element in the metal-based detergent × the metal element content (mol%) / the soap group content (mol%). The metal elements are calcium, magnesium, and the like. The soap group means a sulfonic acid group, a phenol group, a salicylic acid group, and the like.

The blending amount of the metallic detergent is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, and 0.5% by mass based on the total amount of the lubricating oil composition. More preferably, the content is 5% by mass or less.
When the blending amount is 0.01% by mass or more, it becomes easy to obtain performances such as high-temperature cleanliness, oxidation stability, and base number maintenance. On the other hand, if it is 20% by mass or less, an effect commensurate with the amount added is usually obtained, but the upper limit of the amount of the metallic detergent is as low as possible regardless of the above range. It is important to do. As a result, the metal content of the lubricating oil composition, that is, the sulfated ash content, can be reduced to prevent the deterioration of the exhaust gas purification device of the automobile.
Moreover, as long as a metal type detergent contains said prescribed amount, you may use it individually or in combination of 2 or more types.

  Specifically, overbased calcium salicylate or overbased calcium phenate is particularly preferable among the metal detergents, and the polybutenyl succinic acid bisimide is particularly preferable among the ashless dispersants. The total base number of the overbased calcium salicylate and the overbased calcium phenate is preferably from 100 mgKOH / g to 500 mgKOH / g, more preferably from 200 mgKOH / g to 500 mgKOH / g.

Examples of the viscosity index improver include polymethacrylate, dispersed polymethacrylate, olefin copolymer (for example, ethylene-propylene copolymer), dispersed olefin copolymer, styrene copolymer (for example, Styrene-diene copolymer, styrene-isoprene copolymer, etc.).
The blending amount of the viscosity index improver is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less based on the total amount of the lubricating oil composition from the viewpoint of the blending effect.

Examples of the pour point depressant include polymethacrylate having a mass average molecular weight of about 5,000 to 50,000.
The blending amount of the pour point depressant is preferably 0.1% by mass or more and 2% by mass or less, more preferably 0.1% by mass or more and 1% by mass or less, based on the total amount of the lubricating oil composition, from the viewpoint of the blending effect. is there.

Examples of the metal deactivator include benzotriazole, tolyltriazole, thiadiazole, and imidazole compounds.
The compounding amount of the metal deactivator is preferably 0.01% by mass or more and 3% by mass or less, more preferably 0.01% by mass or more and 1% by mass or less, based on the total amount of the lubricating oil composition.

Examples of the rust preventive include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinate, polyhydric alcohol ester and the like.
The blending amount of these rust preventives is preferably 0.01% by mass or more and 1% by mass or less, more preferably 0.05% by mass or more and 0.5% by mass based on the total amount of the lubricating oil composition from the viewpoint of the blending effect. It is as follows.

  Examples of the antifoaming agent include silicone oil, fluorosilicone oil, and fluoroalkyl ether. The blending amount is 0.00 on the basis of the total amount of the lubricating oil composition from the viewpoint of balance of antifoaming effect and economy. 005 mass% or more and 0.5 mass% or less are preferable, More preferably, they are 0.01 mass% or more and 0.2 mass% or less.

  In the lubricating oil composition of the present invention, a friction modifier, an antiwear agent, and an extreme pressure agent may be further blended as necessary. In addition, this friction modifier refers to compounds other than the polar group containing compound which is an essential component of this invention. The blending amount of the friction modifier is preferably 0.01% by mass or more and 2% by mass or less, more preferably 0.01% by mass or more and 1% by mass or less, based on the total amount of the lubricating oil composition.

  Examples of the antiwear or extreme pressure agent include zinc dithiophosphate, zinc phosphate, zinc dithiocarbamate, molybdenum dithiocarbamate, molybdenum dithiophosphate, disulfides, sulfurized olefins, sulfurized fats and oils, sulfurized esters, thiocarbonates, Sulfur-containing compounds such as thiocarbamates and polysulfides; phosphorous esters, phosphate esters, phosphonate esters, and phosphorus-containing compounds such as amine salts or metal salts thereof; thiophosphites, thiophosphorus And sulfur and phosphorus containing antiwear agents such as acid esters, thiophosphonic acid esters, and amine salts or metal salts thereof.

  When blending antiwear or extreme pressure agents, it is necessary to pay attention so that the content of phosphorus and metals in the lubricant is not excessive when blending antiwear or extreme pressure agents. There is.

The lubricating oil composition of the present invention is composed of the above composition, and satisfies the following as its properties.
(1) The sulfated ash content (JIS K2272) is less than 0.3% by mass, preferably 0.25% by mass or less. And,
(2) The phosphorus content (JIS-5S-38-92) is 0.03% by mass or more and 0.06% by mass or less, preferably 0.03% by mass or more and 0.055% by mass or less.
(3) The sulfur content (JIS K2541) is 0.10% by mass or more and 1.00% by mass or less, preferably 0.12% by mass or more and 0.90% by mass or less.
In addition to the above, it is more preferable to satisfy the following.
(4) The nitrogen content (JIS K 2609) is preferably 0.08 mass% or more and 0.40 mass% or less, more preferably 0.08 mass% or more and 0.35 mass% or less.
(5) The boron content (JPI-5S-38-92) is preferably 0.020 mass% or more and 0.3 mass% or less, more preferably 0.025 mass% or more and 0.25 mass% or less.
The lubricating oil composition of the present invention satisfying these properties significantly increases ZnDTP and metallic detergents containing a large amount of phosphorus while maintaining wear resistance against aluminum alloys in an engine whose sliding part is an aluminum alloy. Can be reduced.

  The lubricating oil composition of the present invention can be preferably used as a lubricating oil for internal combustion engines such as motorcycles, automobiles, gasoline engines for power generation, marine use, diesel engines, gas engines, etc., and has a low phosphorus content and low sulfur content. Therefore, it is particularly suitable for an internal combustion engine equipped with an exhaust gas purification device.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.
<Method for measuring properties and performance>
The properties and performances of the lubricating oil compositions in the following examples and comparative examples were determined by the following methods.

(1) Phosphorus content It measured based on JPI-5S-38-92.
(2) Sulfur content It measured based on JISK2541.
(3) Boron content It measured based on JPI-5S-38-92.
(4) Sulfated ash content Measured according to JIS K 2272.
(5) Nitrogen content It measured based on JISK2609.

(6) Evaluation of wear resistance Using an SRV friction tester (reciprocating friction tester), the surface of the ring-shaped steel material is moved back and forth in contact with the disk under the following test conditions. A friction test was performed and the maximum coefficient of dynamic friction during the test time was measured. If this dynamic friction coefficient exceeds 0.3 within the test time, the disk of the test piece is greatly worn, so that wear resistance becomes a problem.
-Test conditions-
Test piece: Ring-shaped steel (chromium-plated steel, ring width: 1.5 mm), disk (Si-containing aluminum: AA (American Aluminum Association) standard “A390”)
Test temperature: 130 ° C
・ Load: 100N
・ Moving direction: Ring steel width direction ・ Amplitude: 3.0 mm
・ Frequency: 20Hz
・ Test time: 1 hour (However, the test is stopped when the dynamic friction coefficient exceeds 0.3)

<Examples 1-11 and Comparative Examples 1-6>
As shown in Tables 1 and 2, engine oil compositions were prepared by blending base oil and additives in respective proportions. The properties and performance of these compositions are summarized in Tables 1 and 2.

In addition, each component used for preparation of the lubricating oil composition shown in Table 1 and Table 2 is as follows.
Base oil: hydrorefined mineral oil (100 N, 40 ° C. kinematic viscosity: 21.0 mm ² / s, 100 ° C. kinematic viscosity: 4.5 mm ² / s, viscosity index: 127, sulfur content: less than 5 ppm by mass)
Boron imide 1 (polybutenyl succinic acid monoimide borate, polybutenyl group number average molecular weight: 950, base number (perchloric acid method): 30.6 mg KOH / g, nitrogen content: 1.8% by mass, Boron content: 2.1% by mass)
・ Boronized imide 2 (polybutenyl succinic acid bisimide borated product, polybutenyl group number average molecular weight: 950, base number (perchloric acid method): 25 mgKOH / g, nitrogen content: 1.2% by mass, boron content (Amount: 1.3% by mass)
Non-boronated imide 1 (polybutenyl succinic acid monoimide, polybutenyl group number average molecular weight: 950, base number (perchloric acid method): 44 mg KOH / g, nitrogen content: 2.1 mass%)
Non-boronated imide 2 (polybutenyl succinic acid bisimide, number average molecular weight of polybutenyl group: 1300, base number (perchloric acid method): 11.9 mg KOH / g, nitrogen content: 1.0 mass%)

Compound A (compound represented by formula (Ia))
Compound B (compound represented by formula (Ib))
Compound C (compound represented by formula (Ic))
Compound D (compound represented by formula (Id))
Compound E (compound represented by formula (Ie))
Compound F (compound represented by formula (If))
Compound G (bis (n-octoxycarbonylmethyl) disulfide, sulfur content: 158 mass ppm)
Phosphorous antiwear agent (zinc dithioalkyldithiophosphate (a mixture of an alkyl group is a secondary butyl group and a secondary hexyl group), Zn content: 9.0% by mass, phosphorus content: 8.0% by mass , Sulfur content: 17.1% by mass)
Other additives: Mixtures with antioxidants (phenolic antioxidants and amine antioxidants), metal deactivators (alkylbenzotriazoles) and antifoaming agents (silicone type)

From Tables 1 and 2, the following can be understood.
It can be seen that the lubricating oil composition of the present invention containing the sulfur-containing heterocyclic compound represented by the general formula (I) has a small coefficient of dynamic friction with respect to an aluminum material and excellent wear resistance (Examples 1 to 11). . In particular, the wear resistance of the lubricating oil composition of Example 4 using the sulfur-containing heterocyclic compound represented by the formula (Ib) with respect to the aluminum material is further remarkable.
On the other hand, any lubricating oil composition containing no sulfur-based antiwear agent or using a sulfur-based antiwear agent other than the sulfur-containing heterocyclic compound represented by the general formula (I) is an aluminum material. Is inferior in wear resistance (Comparative Examples 1 to 6).

The aluminum alloy engine lubricating oil composition of the present invention has excellent wear resistance against aluminum materials, and maintains ZnDTP and metal detergent containing a large amount of phosphorus while maintaining wear resistance against aluminum materials. It can be greatly reduced.
Therefore, it can be effectively used as an engine lubricating oil composition that can reduce the influence on the exhaust gas aftertreatment device of an internal combustion engine using an aluminum material.

Claims (8)

A base oil, a succinimide compound, and a sulfur-containing heterocyclic compound represented by the following general formula (I):
The sulfur content based on the total amount of the composition is 0.10% by mass to 1.00% by mass, the phosphorus content based on the total amount of the composition is 0.03% by mass to 0.06% by mass, and sulfuric acid An aluminum alloy engine lubricating oil composition having an ash content of less than 0.3% by mass.

(In the formula, As is a sulfur-containing heterocycle, R ¹ and R ² are each independently a hydrogen atom, an amino group, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, and an aryl group. Or a hydrocarbon group having 50 to 50 carbon atoms; or a hydrocarbon group having 1 to 50 carbon atoms containing an atom selected from an oxygen atom, a nitrogen atom and a sulfur atom in the hydrocarbon group. , L, m and n are each independently an integer of 0 or more and 5 or less.)   The aluminum oil engine lubricating oil composition according to claim 1, wherein the nitrogen content derived from the succinimide compound is 0.08% by mass or more and 0.40% by mass or less based on the total amount of the composition.   The lubricating oil composition for an aluminum alloy engine according to claim 2, wherein the succinimide compound contains a boron derivative thereof.   The lubricating oil composition for an engine made of an aluminum alloy according to any one of claims 1 to 3, wherein in the general formula (I), both m and n are not 0.   The lubricating oil composition for an aluminum alloy engine according to any one of claims 1 to 4, wherein in the general formula (I), the sulfur-containing heterocycle is a thiadiazole ring.   The lubricating oil for an aluminum alloy engine according to claim 5, wherein the thiadiazole ring is a 1,3,4-thiadiazole ring, and sulfur atoms are bonded to positions 2 and 5 of the 1,3,4-thiadiazole ring. Composition.   The lubricating oil composition for an aluminum alloy engine according to claim 6, wherein one sulfur atom is bonded to each of positions 2 and 5 of the 1,3,4-thiadiazole ring.   An engine having a sliding part made of an aluminum alloy, wherein the lubricating composition for an aluminum alloy engine according to any one of claims 1 to 7 is used for the sliding part. Method.