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.

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.

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).

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).

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.

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.

Low molecular weight, highly branched polyolefins are provided. Also provided are catalyst-mediated methods of making the low molecular weight, highly branched polyolefins and a catalyst system for carrying out the methods. The catalyst system is a homogeneous catalytic system that includes a single-site organozirconium complex and hydrocarbon-soluble perfluoroarylborate co-catalyst that is highly active for the oligomerization of olefin monomers in non-polar media.

Low molecular weight, highly branched polyolefins are provided. Also provided are catalyst-mediated methods of making the low molecular weight, highly branched polyolefins and a catalyst system for carrying out the methods. The catalyst system is a homogeneous catalytic system that includes a single-site organozirconium complex and hydrocarbon-soluble perfluoroarylborate co-catalyst that is highly active for the oligomerization of olefin monomers in non-polar media.

A lubricating oil composition includes an ethylene/α-olefin copolymer (A) having 70 to 90 mole % of structural units derived from ethylene and an intrinsic viscosity [η] of 0.3 to 1.0 dl/g.