Lubricating oil composition

Abstract

The present invention provides a lubricating oil composition that is a lubricating oil composition with a 150° C. HTHS viscosity of less than 2.6 mPa·s and can be reduced sufficiently in the 40° C. kinematic viscosity, 100° C. kinematic viscosity and 100° C. HTHS viscosity and suppress the increase of the friction coefficient in a boundary lubrication region and has excellent fuel saving properties. The lubricating oil composition comprises a lubricating base oil with a 100° C. kinematic viscosity of 1 to 5 mm 2 /s; (A) a viscosity index improver with a weight average molecular weight of 400,000 or less and a PSSI of 20 or less; (B) an overbasic metallic detergent with a metal ratio of 3.4 or less; and (C) a friction modifier, and having a 150° C. HTHS viscosity of lower than 2.6 mPa·s.

1 . A lubricating oil composition comprising:
 a lubricating base oil with a 100° C. kinematic viscosity of 1 to 5 mm 2 /s;
 (A) a viscosity index improver with a weight average molecular weight of 400,000 or less and a PSSI of 20 or less; 
 (B) an overbasic metallic detergent with a metal ratio of 3.4 or less; and 
 (C) a friction modifier, 
   and having a 150° C. HTHS viscosity of lower than 2.6 mPa·s.   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the viscosity index improver is a viscosity index improver with a ratio of the weight-average molecular weight and PSSI (Mw/PSSI) of 1×10 4  or greater. 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the overbasic metallic detergent is an overbasic alkaline earth metal salicylate produced by overbasing an alkaline earth metal salicylate with an alkaline earth metal borate. 
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein the friction modifier is preferably an organic molybdenum friction modifier. 
     
     
         5 . The lubricating oil composition according to  claim 2 , wherein the overbasic metallic detergent is an overbasic alkaline earth metal salicylate produced by overbasing an alkaline earth metal salicylate with an alkaline earth metal borate. 
     
     
         6 . The lubricating oil composition according to  claim 2 , wherein the friction modifier is preferably an organic molybdenum friction modifier. 
     
     
         7 . The lubricating oil composition according to  claim 3 , wherein the friction modifier is preferably an organic molybdenum friction modifier.