Lubricating oil composition

Abstract

The present invention provides a lubricating oil composition exhibit excellent friction reduction properties with a small amount of molybdenum. The lubricating oil composition comprises a lubricating base oil, (A) a phosphoric acid ester metal salt represented by formula (1) and (B) an organic molybdenum compound with a ratio of molybdenum to sulfur of 1:3.5 or greater. (In formula 1, R 1 to R 4 are each a hydrocarbon group having 1 to 30 carbon atoms, an alkyl or alkenyl group having 1 to 30 carbon atoms, or an alkylthioethyl comprising an alkyl group having 1 to 30 carbon atoms and may be the same or different from each other; X 1 , X 2 , X 3 and X 4 are each sulfur or oxygen, either X 1 or X 2 is oxygen or both are oxygen, and either X 3 or X 4 is oxygen or both are oxygen; and Y is a metal element.)

1 . A lubricating oil composition comprising a lubricating base oil, (A) a phosphoric acid ester metal salt represented by formula (1) and (B) an organic molybdenum compound with a ratio of molybdenum to sulfur of 1:3.5 or greater: 
       
         
           
           
               
               
           
         
       
       wherein R 1  to R 4  are each a hydrocarbon group having 1 to 30 carbon atoms, an alkyl or alkenyl group having 1 to 30 carbon atoms, or an alkylthioethyl comprising an alkyl group having 1 to 30 carbon atoms and may be the same or different from each other; X 1 , X 2 , X 3  and X 4  are each sulfur or oxygen, either X 1  or X 2  is oxygen or both are oxygen, and either X 3  or X 4  is oxygen or both are oxygen; and Y is a metal element. 
     
     
         2 . The lubricating oil composition according to  claim 1  wherein R 1  through R 4  are each a straight-chain alkyl group having 4 to 8 carbon atoms. 
     
     
         3 . The lubricating oil composition according to  claim 1  further comprising an ashless dispersant containing no boron. 
     
     
         4 . The lubricating oil composition according to  claim 2  further comprising an ashless dispersant containing no boron.