| 摘要 |
PROBLEM TO BE SOLVED: To provide a viscosity index improver which has an excellent shear stability and yields a highly economical lubricating oil composition, and a lubricating oil composition containing this. SOLUTION: The viscosity index improver for lubricating oils comprises an olefin polymer of at least oneα-olefin chosen from 2-20Cα-olefins having a number average molecular weight of from 20,000 to 2,000,000 and a ratio Mw/Mn (wherein Mw is the weight average molecular weight; and Mn is the number average molecular weight) of <=1.5. The lubricating oil composition contains the viscosity index improver, a lubricating oil base material and, if required, a pour point-depressant. |
