| 摘要 |
PURPOSE:To obtain an additive composition which is excellent in solubility in a lubricating oil and gives a lubricating oil composition having a high viscosity index and an excellent shear stability by using a specified carbonate, a plurality of specified copolymers, and a polyalkyl (meth)acrylate as the constituents. CONSTITUTION:This composition contains a carbonate represented by the formula R<1>-O-C(=O)-O-R<2> (wherein R<1> and R<2> are each alkyl, cycloalkyl, cycloalkyl- alkyl, aryl, aralkyl, or an alkyl or aralkyl ether containing an ether oxygen atom), an oil-soluble ethylene/alpha-olefin random copolymer (e.g. ethylene/propylene random copolymer) having an intrinsic viscosity of 0.25-2.0dl/g, a graft copolymer of this copolymer with an alkyl (preferably a 1-22C alkyl) (meth)acrylate, and a polyalkyl (meth)acrylate preferably made from a 1-22C alkyl monomer. |
