Lubricant compositions comprising a base oil, one or more antioxidants selected from a group consisting of N--naphthyl-N-phenylamine antioxidants and diphenylamine antioxidants; and a sulfur-containing additive comprising up to seven carbon atoms exhibit outstanding oxidative stability and non-corrosion properties. The N--naphthyl-N-phenylamine antioxidants plus diphenylamine antioxidants in total may be present from about 0.2 wt % to about 0.8 wt %, based on the total weight of the lubricant composition. The sulfur provided by the sulfur-containing additive may be present from about 50 ppm to about 1000 ppm by weight, based on the total weight of the lubricant composition.

Lubricant compositions comprising a base oil, one or more antioxidants selected from a group consisting of N--naphthyl-N-phenylamine antioxidants and diphenylamine antioxidants; and a sulfur-containing additive comprising up to seven carbon atoms exhibit outstanding oxidative stability and non-corrosion properties. The N--naphthyl-N-phenylamine antioxidants plus diphenylamine antioxidants in total may be present from about 0.2 wt % to about 0.8 wt %, based on the total weight of the lubricant composition. The sulfur provided by the sulfur-containing additive may be present from about 50 ppm to about 1000 ppm by weight, based on the total weight of the lubricant composition.

An object of the present invention is to provide a dialkyl sulfide which can effectively form a metal sulfide film on a metal surface even in a low-temperature environment, has excellent storage stability, and is suitable as an extreme-pressure additive. The present invention provides a dialkyl sulfide represented by general formula (1) below (in the formula, R.sup.1 and R.sup.2 each independently represent an alkyl group, and n is an integer), wherein the content of a compound having an n value of 1 in the general formula (1) is 10.0% by mass or less relative to the total amount of compounds represented by the general formula (1)

##STR00001##

An object of the present invention is to provide a dialkyl sulfide which can effectively form a metal sulfide film on a metal surface even in a low-temperature environment, has excellent storage stability, and is suitable as an extreme-pressure additive. The present invention provides a dialkyl sulfide represented by general formula (1) below (in the formula, R.sup.1 and R.sup.2 each independently represent an alkyl group, and n is an integer), wherein the content of a compound having an n value of 1 in the general formula (1) is 10.0% by mass or less relative to the total amount of compounds represented by the general formula (1)

##STR00001##

A deposition composition includes a solvent comprising a hydrofluorothioether compound represented by the following general formula (I): RfSRh where Rf is a fluorinated or perfluorinated group having 2-9 carbon atoms and optionally includes one or more catenated heteroatoms or chlorine atoms, and Rh is a non-fluorinated hydrocarbon group having 1-3 carbon atoms. The deposition composition further includes a coating material that is soluble or dispersible in said solvent.

A deposition composition includes a solvent comprising a hydrofluorothioether compound represented by the following general formula (I): RfSRh where Rf is a fluorinated or perfluorinated group having 2-9 carbon atoms and optionally includes one or more catenated heteroatoms or chlorine atoms, and Rh is a non-fluorinated hydrocarbon group having 1-3 carbon atoms. The deposition composition further includes a coating material that is soluble or dispersible in said solvent.

An object of the invention is to provide a grease composition that does not deteriorate resin, particularly, acetal resin, in contact therewith even under a high temperature condition. The object can be attained by a grease composition for resin, including (A) a lubricating base oil, (B) a thickener, and (C) at least one selected from the group consisting of an organic molybdenum compound and a sulfur-based extreme pressure agent, wherein when the grease composition includes the sulfur-based extreme pressure agent, a content of the sulfur-based extreme pressure agent is from 0.05 mass % to 2.5 mass % based on a total amount of the composition, and the grease composition is substantially free of zinc dialkyldithiophosphate.

An object of the invention is to provide a grease composition that does not deteriorate resin, particularly, acetal resin, in contact therewith even under a high temperature condition. The object can be attained by a grease composition for resin, including (A) a lubricating base oil, (B) a thickener, and (C) at least one selected from the group consisting of an organic molybdenum compound and a sulfur-based extreme pressure agent, wherein when the grease composition includes the sulfur-based extreme pressure agent, a content of the sulfur-based extreme pressure agent is from 0.05 mass % to 2.5 mass % based on a total amount of the composition, and the grease composition is substantially free of zinc dialkyldithiophosphate.

For efficiently producing a dialkyl polysulfide which is able to be favorably used as an extreme-pressure additive which does not easily corrode the metal surface, and an extreme-pressure additive and lubricating fluid composition including the dialkyl polysulfide, provided is a method for producing dialkyl polysulfide including a first step of reacting an olefin compound (a) represented by General Formula (1): R.sup.1R.sup.2CCHR.sup.3 (where R.sup.1 and R.sup.2 each are an alkyl group, R.sup.3 is a hydrogen atom or an alkyl group, and the total number of carbon atoms of R.sup.1, R.sup.2 and R.sup.3 is 2 to 20) with sulfur in the presence of a hydrogen sulfide to thereby obtain crude dialkyl polysulfide (A), and a second step of reacting the crude dialkyl polysulfide (A) and a sulfide of an alkali metal in a solvent including an alcohol to thereby reduce the number of sulfur atoms in the crude dialkyl polysulfide (A).

For efficiently producing a dialkyl polysulfide which is able to be favorably used as an extreme-pressure additive which does not easily corrode the metal surface, and an extreme-pressure additive and lubricating fluid composition including the dialkyl polysulfide, provided is a method for producing dialkyl polysulfide including a first step of reacting an olefin compound (a) represented by General Formula (1): R.sup.1R.sup.2CCHR.sup.3 (where R.sup.1 and R.sup.2 each are an alkyl group, R.sup.3 is a hydrogen atom or an alkyl group, and the total number of carbon atoms of R.sup.1, R.sup.2 and R.sup.3 is 2 to 20) with sulfur in the presence of a hydrogen sulfide to thereby obtain crude dialkyl polysulfide (A), and a second step of reacting the crude dialkyl polysulfide (A) and a sulfide of an alkali metal in a solvent including an alcohol to thereby reduce the number of sulfur atoms in the crude dialkyl polysulfide (A).