A lubricating oil composition for automobile transmissions including a lubricant base oil, and a liquid random copolymer of ethylene and α-olefin, the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 4.0 to 7.5 mm.sup.2/s, and a Brookfield viscosity at −40° C. of 20,000 mPa.Math.s or less, and wherein the lubricant base oil consists of a mineral oil with a kinematic viscosity at 100° C. of 2 to 10 mm.sup.2/s, a viscosity index of 105 or more, and a pour point of −10° C. or lower, and/or a synthetic oil with a kinematic viscosity at 100° C. of 1 to 10 mm.sup.2/s, a viscosity index of 120 or more, and a pour point of −30° C. or lower.

A lubricating oil composition for automobile transmissions including a lubricant base oil, and a liquid random copolymer of ethylene and α-olefin, the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 4.0 to 7.5 mm.sup.2/s, and a Brookfield viscosity at −40° C. of 20,000 mPa.Math.s or less, and wherein the lubricant base oil consists of a mineral oil with a kinematic viscosity at 100° C. of 2 to 10 mm.sup.2/s, a viscosity index of 105 or more, and a pour point of −10° C. or lower, and/or a synthetic oil with a kinematic viscosity at 100° C. of 1 to 10 mm.sup.2/s, a viscosity index of 120 or more, and a pour point of −30° C. or lower.

A lubricating oil composition for automobile gears, including a lubricant base oil and a liquid random copolymer of ethylene and α-olefin(s), the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 7 to 30 mm.sup.2/s, and wherein the lubricant base oil consists of a mineral oil having a kinematic viscosity at 100° C. of 2 to 10 mm.sup.2/s, a viscosity index of 105 or more and a pour point of −10° C. or lower, and/or a synthetic oil having a kinematic viscosity at 100° C. of 1 to 10 mm.sup.2/s, a viscosity index of 120 or more and a pour point of −30° C. or lower.

A lubricating oil composition for automobile gears, including a lubricant base oil and a liquid random copolymer of ethylene and α-olefin(s), the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 7 to 30 mm.sup.2/s, and wherein the lubricant base oil consists of a mineral oil having a kinematic viscosity at 100° C. of 2 to 10 mm.sup.2/s, a viscosity index of 105 or more and a pour point of −10° C. or lower, and/or a synthetic oil having a kinematic viscosity at 100° C. of 1 to 10 mm.sup.2/s, a viscosity index of 120 or more and a pour point of −30° C. or lower.

A lubricating oil composition for compressor oils, including 10 to 99% by mass of a lubricant base oil (A) having a kinematic viscosity at 100° C. of 1 to 14 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, and 90 to 1% by mass of a liquid random copolymer ethylene-α-olefin copolymer (B) of ethylene and α-olefin, the liquid random copolymer ethylene-α-olefin copolymer (B) being prepared by means of a specific catalyst (where the total amount of (A) and (B) is 100% by mass), the lubricating oil composition for compressor oils having a kinematic viscosity at 40° C. of 10 to 300 mm.sup.2/s.

A lubricating oil composition for compressor oils, including 10 to 99% by mass of a lubricant base oil (A) having a kinematic viscosity at 100° C. of 1 to 14 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, and 90 to 1% by mass of a liquid random copolymer ethylene-α-olefin copolymer (B) of ethylene and α-olefin, the liquid random copolymer ethylene-α-olefin copolymer (B) being prepared by means of a specific catalyst (where the total amount of (A) and (B) is 100% by mass), the lubricating oil composition for compressor oils having a kinematic viscosity at 40° C. of 10 to 300 mm.sup.2/s.

The present invention is a lubrication oil composition which is characterized by containing (A) a liquid random copolymer of ethylene and an α-olefin, which is produced by a specific method and (F) a sulfur-containing compound wherein at least one hydrocarbon group that is adjacent to a sulfur atom is a secondary or tertiary hydrocarbon group, while containing, as an optional component, (G) a polymer of an α-olefin having 3 to 6 carbon atoms, and which is also characterized in that: the kinematic viscosity at 40° C. is 450 to 51,000 mm.sup.2/s; the content of sulfur is 0.1 to 5 parts by weight; and the content of the component (G) is 0 to 15 parts by weight. This lubrication oil composition is especially suitable for gear oils and the like.

A lubricating oil composition for internal combustion engines, including a lubricant base oil and 3% by mass or more, but less than 40% by mass of a liquid random copolymer of ethylene and an α-olefin, the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 6.9 mm.sup.2/s or more, but less than 12.5 mm.sup.2/s, and wherein the lubricant base oil consists of a mineral oil having a kinematic viscosity at 100° C. of 2 to 7 mm.sup.2/s, a viscosity index of 105 or more and a pour point of −10° C. or lower, and/or a synthetic oil having a kinematic viscosity at 100° C. of 1 to 7 mm.sup.2/s, a viscosity index of 120 or more and a pour point of −30° C. or lower.

A lubricating oil composition for internal combustion engines, including a lubricant base oil and 3% by mass or more, but less than 40% by mass of a liquid random copolymer of ethylene and an α-olefin, the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 6.9 mm.sup.2/s or more, but less than 12.5 mm.sup.2/s, and wherein the lubricant base oil consists of a mineral oil having a kinematic viscosity at 100° C. of 2 to 7 mm.sup.2/s, a viscosity index of 105 or more and a pour point of −10° C. or lower, and/or a synthetic oil having a kinematic viscosity at 100° C. of 1 to 7 mm.sup.2/s, a viscosity index of 120 or more and a pour point of −30° C. or lower.

The present invention relates to the use of a lubricating composition comprising: —at least one base oil; and—at least one monoester which is separate from the base oil and formed between a linear, saturated or unsaturated C.sub.8-C.sub.14 monocarboxylic acid, and a branched, saturated or unsaturated C.sub.4-C.sub.16 monoalcohol to reduce the fuel consumption of a vehicle fitted with a transmission member, in particular a gearbox and/or an axle, which is lubricated by means of said composition.