Lubricating oil composition

Abstract

The present invention provides a lubricating oil composition improved in fuel-saving properties by reducing lubrication resistance within the same viscosity grade oils. The lubricating oil composition comprises a lubricating base oil and a viscosity index improver with a PSSI of 30 or lower blended such that the viscosity index of the composition is 160 or greater and the 100° C. kinematic viscosity loss after shearing is 15 percent or less.

1 . A lubricating oil composition comprising a lubricating base oil and a viscosity index improver with a PSSI of 30 or lower blended such that the viscosity index of the composition is 160 or greater and the 100° C. kinematic viscosity loss after shearing is 15 percent or less. 
   
   
       2 . The lubricating oil composition according to  claim 1 , wherein the viscosity index improver is a styrene-diene copolymer viscosity index improver with a PSSI of 30 or lower. 
   
   
       3 . The lubricating oil composition according to  claim 1 , wherein the viscosity index improver is a polymethacrylate viscosity index improver with a PSSI of 15 or lower. 
   
   
       4 . The lubricating oil composition according to  claim 1 , wherein the 100° C. TBS viscosity of the composition is 7 mPa·s or lower. 
   
   
       5 . The lubricating oil composition according to  claim 1 , wherein the 100° C. kinematic viscosity of the composition is from 9.3 to 11.0 mm 2 /s, the 40° C. kinematic viscosity is from 40 to 60 mm 2 /s and the 100° C. kinematic viscosity after shearing is 9.3 mm 2 /s or higher. 
   
   
       6 . The lubricating oil composition according to  claim 1 , further comprising a metal salt of a phosphorus-containing acid ester. 
   
   
       7 . The lubricating oil composition according  claim 1 , further comprising a metallic detergent, an ashless dispersant, and an anti-oxidant. 
   
   
       8 . The lubricating oil composition according to  claim 1 , wherein the sulfated ash content is from 0.1 to 2 percent by mass.