The present invention provides a viscosity index improver having an excellent viscosity index improving effect, a lubricant composition having excellent low-temperature viscosity in which the viscosity reduction due to long-term use is small, and a method for producing the lubricant composition. A viscosity index improver of the present invention contains a copolymer (A) containing, as monomer units, an alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms, and an alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms, wherein the alkyl group of the alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms has a molar-average carbon number (Q) of 29 or more, and the alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms is contained as a monomer unit in an amount of 38 to 75% by weight based on the weight of the copolymer (A).

The present invention relates to novel uses of corrosion inhibitors in fuels and lubricants.

A lubricant composition of (a) an oil of lubricating viscosity; (b) a poly(meth)acrylate ester polymer comprising 0.5 to 5 weight percent of amine nitrogen-containing dispersant monomer units and (c) an esterified copolymer with a backbone comprising units derived from (i) an -olefin monomer of at least about 6 carbon atoms, (ii) an ethylenically unsaturated carboxylic acid or derivative thereof, further containing nitrogen functionality in groups pendant from the copolymer backbone, provides a good combination of seal performance and oxidation resistance.

The invention provides a lubricating composition containing an oil of lubricating viscosity and a block copolymer. The block copolymer may contain (a) a hydrophobic first block having C.sub.1-30 alkyl (meth)acrylic units, wherein at least 50 wt % of the C.sub.1-30 alkyl (meth)acrylic units are C.sub.12-15 alkyl (meth)acrylic units, and up to 50 wt % of the C.sub.1-30 alkyl (meth)acrylic units are C.sub.16-20 alkyl (meth)acrylic units, with the proviso that alkyl groups of the C.sub.1-30 alkyl (meth)acrylic units have an average total number of carbon atoms of at least 8; and (b) a second block having (meth)acrylic units further having a heteroatom-containing group providing a polar group. The invention further relates to a method of lubricating an internal combustion engine by lubricating the engine with the lubricating composition. The invention further relates to the use of the block copolymer as an emulsifier and/or pour point depressant.

The present invention relates to novel uses of corrosion inhibitors in fuels and lubricants.

The present invention aims to provide a viscosity index improver excellent in shear stability and having a low HTHS viscosity and a high viscosity index. The viscosity index improver of the present invention contains a (co)polymer (A) containing a polyolefin-based monomer as an essential monomer unit, and a base oil, wherein the absolute value of difference in solubility parameter between the (co)polymer (A) and the base oil is 0.8 to 2.0 (cal/cm.sup.3).sup.1/2.

The present invention relates to novel uses of corrosion inhibitors in fuels and lubricants.

This invention relates to a lubricating oil composition comprising: at least 50 mass % or more of one or more base oils; detergent; and 0.01 to 20 mass % of a functionalized polymer comprising a partially or fully saturated olefin homopolymer or copolymer backbone and at least one functional group, having: i) an Mn of 10,000 g/mol or more (GPC-PS) of the polymer prior to functionalization, ii) where in the functional group is derived from an acylating agent and a compound containing amino and/or hydroxyl groups, and iii) optionally, wherein the homopolymer or copolymer backbone is derived from monomers selected from the group consisting of C.sub.2 to C.sub.30 (such as linear) alpha olefins and C.sub.4 to C.sub.20 conjugated dienes; where PIBSA-PAM having an Mn of 1,600 g/mol or more (GPC-PS) is absent or substantially absent from the lubricating oil composition, or, if present, is present in an amount such that the weight ratio of the functionalized polymer (B) to the high molecular weight PIBSA-PAM is at least 0.25:1.

The present invention relates to novel uses of corrosion inhibitors in fuels and lubricants.

The present invention aims to provide a viscosity index improver excellent in shear stability and having a low HTHS viscosity and a high viscosity index. The viscosity index improver of the present invention contains a (co)polymer (A) containing a polyolefin-based monomer as an essential monomer unit, and a base oil, wherein the absolute value of difference in solubility parameter between the (co)polymer (A) and the base oil is 0.8 to 2.0 (cal/cm.sup.3).sup.1/2.