A lubricating oil composition for industrial gears, including 10 to 90% by mass of a lubricant base oil (A) having a kinematic viscosity at 100° C. of 1 to 100 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, and 90 to 10% by mass of a liquid random copolymer (B) of ethylene and α-olefin, the liquid random copolymer (B) being prepared by means of a specific catalyst, wherein the total amount of (A) and (B) is 100% by mass, the lubricating oil composition for industrial gears having a kinematic viscosity at 40° C. of 100 to 10,000 mm.sup.2/s.

A grease composition including 10 to 98% 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, 89 to 1% by mass of a liquid random copolymer (B) of ethylene and α-olefin produced by using a specific catalyst, and 1 to 30% by mass of a thickener (C) (note that the sum total of (A) to (C) is 100% by mass), wherein the lubricant base oil (A) and the copolymer (B) are mixed in such a ratio that the mixture of the lubricant base oil (A) and the ethylene-α-olefin copolymer (B) has a kinematic viscosity at 100° C. of 1 to 500 mm.sup.2/s and a viscosity index of 120 or more.

A lubricating oil composition for internal combustion engines, including a lubricant base oil and 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 12.5 mm.sup.2/s or more, but less than 26.1 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 95 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 hydraulic oils including 10 to 99% by mass of a lubricant base oil (A) with 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 (B) of ethylene and α-olefin prepared using a specific catalyst, wherein the total amount of (A) and (B) is 100% by mass, and having a kinematic viscosity at 100° C. of 10 to 300 mm.sup.2/s.

Disclosed are Group III base stocks comprising at least 30 wt % naphthenes, a viscosity index from 120 to 145; and a unique ratio of molecules with multi-ring naphthenes to single ring naphthenes (2R+N/1RN). A method for preparing the base stocks is also disclosed. Also disclosed is a lubricating oil having the base stock as a major component, and an additive as a minor component.

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 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 provides a lubricating oil composition comprising a polymer for improving viscosity, the composition suppressing viscosity increase in low temperature and having an excellent low-temperature property, and having low viscosity decrease caused by shearing. The present invention is a lubricating oil composition containing from 30 to 90% by weight of a liquid random copolymer (A) of ethylene and α-olefin produced by a specific method, and 10 to 70% by weight of a lubricating oil base consisting of one or more components selected from specific synthetic oil (B) or mineral oil (C) (note that the sum total of the components (A), (B) and (C) is 100% by weight).

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.