| 摘要 |
PURPOSE:To obtain a lubricating oil composition for internal combustion engine having excellent abrasion resistance, etc., and good viscosity index without adding a viscosity index improver or minimizing the amount of the improver by compounding a specific amount of a zinc dialkyldithiophosphate to a specific mixed oil. CONSTITUTION:The composition is produced by using a base oil consisting of a mixed oil having a kinetic viscosity of >=4mm<2>/S at 100 deg.C and a viscosity of <=3,000mPa.S at -15 deg.C and composed of (A) 10-30wt.% (preferably 15-25wt.%) of an ester-type synthetic oil selected from diester and polyol ester (especially preferably having a kinetic viscosity of 3-10 mm<2>/S at 100 deg.C, (B) 60-89wt.% (preferably 65-80wt.%) of an alpha-olefin oligomer and (C) 1-20wt.% (preferably 2-13wt.%) of an ethylene. a-olefin oligomer and compounding the base oil with 0.5-3wt.% (based on the total composition) of a zinc dialkyldithiophosphate of formula [R is alkyl provided that 3-6C sec-alkyl group accounts for >=50% (preferably >=70%) of the four alkyl groups. |
