A silicone grease composition having high friction characteristics and wear characteristics is disclosed. The silicone grease composition is provided by adding a zinc salt (B) containing, at a mass ratio from 1:99 to 99:1, a zinc dialkyldithiophosphate (B1) and a zinc dialkyldithiocarbamate (B2) as an extreme-pressure additive to a silicone oil (A). A method for transmitting torque of a clutch or a torque limiter mechanism is also disclosed.

A silicone grease composition having high friction characteristics and wear characteristics is disclosed. The silicone grease composition is provided by adding a zinc salt (B) containing, at a mass ratio from 1:99 to 99:1, a zinc dialkyldithiophosphate (B1) and a zinc dialkyldithiocarbamate (B2) as an extreme-pressure additive to a silicone oil (A). A method for transmitting torque of a clutch or a torque limiter mechanism is also disclosed.

The present invention provides a lubricating oil additive, including: a molybdenum compound (A) represented by the following general formula (1); and a sulfur-based composition (B) containing a sulfur-based compound (b-1) represented by the following general formula (2) and at least one kind of sulfur-based compound (b-2) represented by the following general formula (3) or (4), and a lubricating oil composition containing the additive. In the formula (1), R.sup.1 to R.sup.4 each represent alkyl groups having 6 to 18 carbon atoms, the groups being identical to or different from each other, and X.sup.1 to X.sup.4 each independently represent an oxygen atom or a sulfur atom. In the formula (2), R.sup.5 represents an alkyl group having 1 to 22 carbon atoms, R.sup.6 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, R.sup.7 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and “a” represents a number from 1 to 10. In the formulae (3) and (4), R.sup.8 to R.sup.11 each represent alkylene groups having 1 to 28 carbon atoms, the groups being identical to or different from each other, R.sup.12 and R.sup.13 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and “b” and “c” each independently represent a number from 1 to 8, provided that at least one of R.sup.12 or R.sup.13 represents an alkyl group having 1 to 3 carbon atoms.

##STR00001##

The present invention provides a lubricating oil additive, including: a molybdenum compound (A) represented by the following general formula (1); and a sulfur-based composition (B) containing a sulfur-based compound (b-1) represented by the following general formula (2) and at least one kind of sulfur-based compound (b-2) represented by the following general formula (3) or (4), and a lubricating oil composition containing the additive. In the formula (1), R.sup.1 to R.sup.4 each represent alkyl groups having 6 to 18 carbon atoms, the groups being identical to or different from each other, and X.sup.1 to X.sup.4 each independently represent an oxygen atom or a sulfur atom. In the formula (2), R.sup.5 represents an alkyl group having 1 to 22 carbon atoms, R.sup.6 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, R.sup.7 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and “a” represents a number from 1 to 10. In the formulae (3) and (4), R.sup.8 to R.sup.11 each represent alkylene groups having 1 to 28 carbon atoms, the groups being identical to or different from each other, R.sup.12 and R.sup.13 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and “b” and “c” each independently represent a number from 1 to 8, provided that at least one of R.sup.12 or R.sup.13 represents an alkyl group having 1 to 3 carbon atoms.

##STR00001##

A crankcase lubricating oil composition for the crankcase of a spark-ignited or compression-ignited internal combustion engine, comprising a magnesium-containing detergent, in an amount sufficient to provide from 200-4000 ppm magnesium to the lubricating oil composition, in combination with an oil-soluble or oil-dispersible molybdenum compound in an amount sufficient to provide from 600-1500 ppm molybdenum atoms to the lubricating oil composition, and with an oil-soluble or oil-dispersible boron-containing compound in an amount sufficient to provide from 200-600 ppm boron atoms to the lubricating oil composition to improve the friction and fuel economy performance.

A crankcase lubricating oil composition for the crankcase of a spark-ignited or compression-ignited internal combustion engine, comprising a magnesium-containing detergent, in an amount sufficient to provide from 200-4000 ppm magnesium to the lubricating oil composition, in combination with an oil-soluble or oil-dispersible molybdenum compound in an amount sufficient to provide from 600-1500 ppm molybdenum atoms to the lubricating oil composition, and with an oil-soluble or oil-dispersible boron-containing compound in an amount sufficient to provide from 200-600 ppm boron atoms to the lubricating oil composition to improve the friction and fuel economy performance.

A method of lubricating the contact between a first surface coated with a hydrogenous carbon film or coating of type a-C:H, ta-C:H, a-C:H:Me or a-C:H:X, as classified by VDI-Standard VDI 2840 and a second ferrous, preferably steel surface. The method comprises supplying to said contact a lubricating oil composition comprising a major amount of an oil of lubricating viscosity and (a) an oil-soluble or oil-dispersible molybdenum compound in an amount such as to provide between 150 and 1000 ppm by weight of molybdenum to the lubricating oil composition, and (b) between 0.1 and 5% by weight with respect to the weight of the lubricating oil composition of a polymeric organic friction modifier, the organic friction modifier being the reaction product of (i) a functionalised polyolefin, (ii) a polyether, (iii) a polyol and (iv) a monocarboxylic acid chain terminating group.

A method of lubricating the contact between a first surface coated with a hydrogenous carbon film or coating of type a-C:H, ta-C:H, a-C:H:Me or a-C:H:X, as classified by VDI-Standard VDI 2840 and a second ferrous, preferably steel surface. The method comprises supplying to said contact a lubricating oil composition comprising a major amount of an oil of lubricating viscosity and (a) an oil-soluble or oil-dispersible molybdenum compound in an amount such as to provide between 150 and 1000 ppm by weight of molybdenum to the lubricating oil composition, and (b) between 0.1 and 5% by weight with respect to the weight of the lubricating oil composition of a polymeric organic friction modifier, the organic friction modifier being the reaction product of (i) a functionalised polyolefin, (ii) a polyether, (iii) a polyol and (iv) a monocarboxylic acid chain terminating group.

An additive composition for a hydraulic fluid, or a heat transfer fluid, comprises one or more phosphate esters derived from the esterification of phosphoric acid and one or more monomer glycols containing up to 18 carbon atoms, or combinations thereof. In addition, the additive composition may comprise one or more corrosion inhibitors selected from the group consisting of dicarboxylic acids, alkanolamines or combinations thereof; one or more antioxidants including selected from the group consisting of one or more organosulfur compounds, one or inorganic oxyanion salts or combinations thereof; and, one or more surfactants.

An additive composition for a hydraulic fluid, or a heat transfer fluid, comprises one or more phosphate esters derived from the esterification of phosphoric acid and one or more monomer glycols containing up to 18 carbon atoms, or combinations thereof. In addition, the additive composition may comprise one or more corrosion inhibitors selected from the group consisting of dicarboxylic acids, alkanolamines or combinations thereof; one or more antioxidants including selected from the group consisting of one or more organosulfur compounds, one or inorganic oxyanion salts or combinations thereof; and, one or more surfactants.