Viscosity index improvers

A lubricating oil composition, comprising:

• (A) 81.4% to 98.97% by weight of a base oil;
• (B) 1 to 3% by weight of a polyalkyl methacrylate based copolymer selected from the group consisting of:
• polymer 1, consisting of 25% by weight of methyl methacrylate (MMA), 5.0% by weight of butyl methacrylate (BMA), 0.1% by weight of isodecyl methacrylate (IDMA), 18.0% by weight of C12-15-alkyl methacrylate having mass average carbon number 13.4 and linear alkyl group content 77% (DPMA), 31.9% by weight of lauryl methacrylate having mass average carbon number 12.5 and containing 73% C12 and 27% C14 all linear alkyl groups (LMA), and 20.0% by weight of stearyl methacrylate having mass average carbon number 17.1 and containing 6% C14 with 30% C16 and 64% C18 all linear alkyl groups (SMA) and having a molar average carbon number of 7.2;
• polymer 2, consisting of 25% by weight of methyl methacrylate (MMA), 55.0% by weight of LMA and 20.0% by weight of SMA and having a molar average carbon number of 7.5;
• polymer 3, consisting of 25% by weight of methyl methacrylate (MMA), 2.5% by weight of butyl methacrylate (BMA), 18.0% by weight of DPMA, 34.5% by weight of LMA and 20.0% by weight of SMA and having a molar average carbon number of 7.4;
• polymer 4, consisting of 25% by weight of methyl methacrylate (MMA), 5.0% by weight of butyl methacrylate (BMA), 0.1% by weight of isodecyl methacrylate (IDMA), 18.0% by weight of DPMA, 29.4% by weight of LMA and 22.5% by weight of SMA and having a molar average carbon number of 7.3;
• polymer 5, consisting of 25% by weight of methyl methacrylate (MMA), 7.0% by weight of butyl methacrylate (BMA), 0.1% by weight of isodecyl methacrylate (IDMA), 18.0% by weight of DPMA, 27.4% by weight of LMA and 22.5% by weight of SMA and having a molar average carbon number of 7.1;
• and
• polymer 6, consisting of 25% by weight of methyl methacrylate (MMA), 5.0% by weight of butyl methacrylate (BMA), 0.1% by weight of isodecyl methacrylate (IDMA), 18.0% by weight of DPMA, 31.9% by weight of LMA and 20.0% by weight of SMA and having a molar average carbon number of 7.2,
• wherein the polyalkyl methacrylate based copolymer has a weight-average molecular weight Mw of from 300,000 g/mol to 1,000,000 g/mol;
• (C) 0 to 0.3% by weight of a polyalkyl (meth)acrylate based copolymer, characterized by a molar average carbon number of 12.0 to 13.0 and a weight-average molecular weight Mw of 10,000 to 100,000 g/mol;
• and
• (D) 0 to 15% by weight of one or more further additives,
• based on the total weight of the lubricating oil composition, wherein the average carbon number corresponds to the molar average of all carbon atoms present in an alkyl residue of an alkyl methacrylate forming the polyalkyl methacrylate based copolymer and the weight-average molecular weight Mw is determined by gel permeation chromatography (GPC) using a polymethylmethacrylate calibration.