Lubricating oil composition

Abstract

Disclosed is a lubricating oil composition comprising: a lubricating base oil comprising 0.5% to 70% by mass of an ester base oil based on the total amount of the lubricating base oil, and having a kinematic viscosity at 40° C. of 18 to 28 mm2/s; and an organic molybdenum compound in an amount of 100 to 1000 mass ppm in terms of the molybdenum element based on the total amount of the lubricating oil composition, wherein the lubricating oil composition has a kinematic viscosity at 40° C. of 50 mm2/s or less.

1 - 4 . (canceled) 
     
     
         5 . A lubricating oil composition comprising:
 a lubricating base oil comprising 1% to 70% by mass of an ester base oil based on the total amount of the lubricating base oil, and said lubricating base oil having a kinematic viscosity at 40° C. of 22 to 26 mm 2 /s; wherein the amount of the lubricating base oil is 67.5% by mass or more; and   molybdenum dithiocarbamate in an amount of 100 to 1000 mass ppm in terms of molybdenum element based on the total amount of the lubricating oil composition, wherein   the lubricating oil composition has a kinematic viscosity at 40° C. of 10 of 50 mm 2 /s or less,   the lubricating oil composition further comprising 2.5% to 24% by mass of a copolymer of an α-olefin and an α,β-ethylenically unsaturated dicarboxylic acid diester, based on the total amount of the lubricating oil composition, wherein the weight-average molecular weight of the copolymer is 6000 to 15000,   the lubricating oil further comprising a boron-containing dispersant in an amount of 100 to 500 mass ppm in terms of boron element based on the total amount of the lubricating oil composition,   wherein the lubricating oil composition is free of styrene-maleic anhydride ester.   
     
     
         6 . The lubricating oil composition according to  claim 5 , wherein the lubricating base oil comprises a synthetic base oil comprising a poly-α-olefin. 
     
     
         7 . A method of lubricating a hypoid gear comprising utilizing the lubricating oil composition of  claim 5 .