Lubricating oil compositions are provided which contain bimodal copolymer compositions, and in particular bimodal ethylene--olefin copolymer compositions. The copolymer compositions comprise first and second ethylene--olefin copolymer components. The bimodal compositions are particularly useful as viscosity or rheology modifiers, e.g., in lubricating oil compositions. Lubricating oil compositions comprising the copolymer compositions advantageously exhibit enhanced shear stability index (SSI) and thickening efficiency (TE) values, while maintaining excellent low-temperature properties such as pour point, mini-rotary viscometer viscosity, and cold crank simulation performance.

Lubricating oil compositions are provided which contain bimodal copolymer compositions, and in particular bimodal ethylene--olefin copolymer compositions. The copolymer compositions comprise first and second ethylene--olefin copolymer components. The bimodal compositions are particularly useful as viscosity or rheology modifiers, e.g., in lubricating oil compositions. Lubricating oil compositions comprising the copolymer compositions advantageously exhibit enhanced shear stability index (SSI) and thickening efficiency (TE) values, while maintaining excellent low-temperature properties such as pour point, mini-rotary viscometer viscosity, and cold crank simulation performance.

Lubricating oil compositions are provided which contain bimodal copolymer compositions, and in particular bimodal ethylene--olefin copolymer compositions. The copolymer compositions comprise first and second ethylene--olefin copolymer components. The bimodal compositions are particularly useful as viscosity or rheology modifiers, e.g., in lubricating oil compositions. Lubricating oil compositions comprising the copolymer compositions advantageously exhibit enhanced shear stability index (SSI) and thickening efficiency (TE) values, while maintaining excellent low-temperature properties such as pour point, mini-rotary viscometer viscosity, and cold crank simulation performance.

Provided are a viscosity modifier for lubricating oils for obtaining an additive composition for lubricating oils having excellent fluidity in a wide temperature range from low temperature to high temperature; and said additive composition for lubricating oils. Further provided are a viscosity modifier for lubricating oils for obtaining a lubricating oil composition capable of reducing viscosity in good balance in a wide temperature range from low temperature to high temperature; and said lubricating oil composition. The viscosity modifier for lubricating oils includes an ethylene -olefin copolymer (A) which includes 30 to 50 mole % of structural units derived from at least one -olefin selected from -olefins having 4 and 5 carbon atoms and 50 to 70 mole % of structural units derived from ethylene (with the proviso that the total of all structural units of said copolymer is 100 mole %) and which satisfies specific requirements (a), (b), and (c).

This disclosure relates to syndiotactic polymers containing units derived from propylene and units derived from C.sub.4 to C.sub.20 alpha olefins. The polymers can be prepared is slurry or solution polymerization processes using a zirconium-containing metallocene catalyst system. The polymers have a melt flow rate as determined by ASTM D-1238 (230 C., 2.16 kg) of from about 0.1 to about 20 g/10 min. The syndiotactic polymers are useful as viscosity index improvers.

This disclosure relates to syndiotactic polymers containing units derived from propylene and units derived from C.sub.4 to C.sub.20 alpha olefins. The polymers can be prepared is slurry or solution polymerization processes using a zirconium-containing metallocene catalyst system. The polymers have a melt flow rate as determined by ASTM D-1238 (230 C., 2.16 kg) of from about 0.1 to about 20 g/10 min. The syndiotactic polymers are useful as viscosity index improvers.

A polymer comprising: a structural unit derived from a compound represented by the following formula (1); and, a structural unit derived from a (meth)acryloyl group-containing compound, wherein the polymer has a content of the structural unit derived from the compound represented by the following formula (1) of 15% by mass or more based on 100% by mass of a total of all structural units, and the polymer has a weight average molecular weight of 5,000 to 500,000.

##STR00001##

A polymer comprising: a structural unit derived from a compound represented by the following formula (1); and, a structural unit derived from a (meth)acryloyl group-containing compound, wherein the polymer has a content of the structural unit derived from the compound represented by the following formula (1) of 15% by mass or more based on 100% by mass of a total of all structural units, and the polymer has a weight average molecular weight of 5,000 to 500,000.

##STR00001##

A viscosity modifier for lubricating oil, including an (C) ethylene--olefin copolymer having an ethylene molar content rate within a range of 30 to 70 mol %, a rotational viscosity at 150 C. of 300 to 8,000 mPa.Math.s, a Hasen chromaticity of 30 or lower, a molecular weight distribution (Mw/Mn) of 2.5 or less, and a B value of 1.1 or more; a lubricating oil composition with a lubricating oil base oil including a (A) mineral oil having a kinematic viscosity at 40 C. of 10 to 100 mm.sup.2/s, a viscosity index of 90 or more, and a pour point of 0 C. or lower and/or a (B) synthetic oil having a kinematic viscosity at 40 C. of 4 to 100 mm.sup.2/s, a viscosity index of 90 or more and a pour point of 30 C. or lower; and the viscosity modifier having has a kinematic viscosity at 40 C. of 28 to 170 mm.sup.2/s.

An object of the present invention is to provide a lubricating oil composition that is particularly excellent in viscosity characteristics at a low temperature of 35 C., i.e., the lubricating oil composition inhibiting an increase in low temperature viscosity while securing a viscosity necessary at an elevated temperature, and being excellent in storage stability in a low temperature environment. The present invention relates to a lubricating oil composition including a copolymer (A) and a base oil (B), in which the copolymer (A) satisfies the following requirement (a-1), and the content ratio between the copolymer (A) and the base oil (B) is such that the copolymer (A) is in a range of 0.1 to 50 parts by mass per 100 parts by mass in total of the copolymer (A) and the base oil (B). (a-1) The copolymer (A) is a copolymer of 4-methyl-1-pentene and an -olefin having 20 or less carbon atoms excluding 4-methyl-1-pentene, including a constituent unit derived from 4-methyl-1-pentene within a range of 1 mol % or more and less than 30 mol % relative to the total constituent units.