LUBRICATING OIL COMPOSITION

摘要

A lubricating oil composition comprises the following (i) to (iii), has a kinematic viscosity at 40°C of not less than 30 mm 2 /s but not more than 750 mm 2 /s and contains boron atoms in an amount of not less than 5 ppmbut not more than 75 ppm; (i) 90 to 10% by mass of a (co) polymer having a kinematic viscosity at 100°C of not more than 45 mm 2 /s and having an acid value of less than 0.1 mgKOH/g, not less than 60% by mol of its constituent units being derived from 1-decene, (ii) 5 to 85% by mass of a (co)polymer having a kinematic viscosity at 100°C of not less than 35 mm 2 /s but not more than 1,500 mm 2 /s and having a molecular weight distribution of not more than 1.8, not less than 90% by mol of its constituent units being derived from 1-octene, and (iii) 5 to 15% by mass of a fatty acid ester, with the proviso that the total amount of (i) to (iii) is 100% by mass.