Lubricating oil composition for internal combustion engine

Abstract

A lubricating oil composition for an internal combustion engine, having (A) a lubricating base oil including one or more mineral oil-based base oils and having a kinematic viscosity at 100° C. of 2.5 mm2/s or more and 4.0 mm2/s or less, and (B) magnesium salicylate in an amount of 0.1 mass % or more and 10 mass % or less based on a total amount of the composition, wherein the composition has an HTHS viscosity at 150° C. of 1.6 mPa·s or more and 2.5 mPa·s or less. The lubricating oil composition for an internal combustion engine has both high fuel-saving performance and LSPI-reducing effect.

1 . A lubricating oil composition for an internal combustion engine, comprising:
 (A) a lubricating base oil including one or more mineral oil-based base oils and having a kinematic viscosity at 100° C. of 2.5 mm 2 /s or more and 4.0 mm 2 /s or less, and   (B) magnesium salicylate in an amount of 0.1 mass % or more and 10 mass % or less based on a total amount of the lubricating oil composition, wherein   the composition has an HTHS viscosity at 150° C. of 1.6 mPa·s or more and 2.5 mPa·s or less.   
     
     
         2 . The lubricating oil composition for an internal combustion engine according to  claim 1 , wherein
 a content of the magnesium salicylate (B) is 0.1 mass % or more and 3.0 mass % or less based on the total amount of the lubricating oil composition,   the lubricating oil composition further comprises (C) a viscosity index improver, and   a content of the viscosity index improver (C) is 0.1 mass % or more and 10 mass % or less based on the total amount of the lubricating oil composition.   
     
     
         3 . The lubricating oil composition for an internal combustion engine according to  claim 1 , further comprising (D) a molybdenum-based friction modifier as a friction modifier in an amount of 0.01 mass % or more and 10 mass % or less based on the total amount of the lubricating oil composition. 
     
     
         4 . The lubricating oil composition for an internal combustion engine according to  claim 1 , wherein the magnesium salicylate has a base number of 350 mgKOH/g or less. 
     
     
         5 . The lubricating oil composition for an internal combustion engine according to  claim 1 , wherein the composition has an HTHS viscosity at 150° C. of 1.6 mPa·s or more and 2.0 mPa·s or less. 
     
     
         6 . The lubricating oil composition for an internal combustion engine according to  claim 1 , wherein the composition has an LSPI frequency index calculated by the following equation (6) of 0 or less: 
       
         
           
             
               
                 
                   
                     
                       LSPI 
                       ⁢ 
                           
                       frequency 
                       ⁢ 
                           
                       index 
                     
                     = 
                     
                       
                         6.59 
                         × 
                         Ca 
                       
                       - 
                       
                         26.6 
                         × 
                         P 
                       
                       - 
                       
                         
                           5 
                           . 
                           1 
                         
                         ⁢ 
                         2 
                         × 
                         Mo 
                       
                       + 
                       1.69 
                     
                   
                 
                 
                   
                     Equation 
                     ⁢ 
                         
                     
                       ( 
                       6 
                       ) 
                     
                   
                 
               
             
           
         
       
       wherein Ca represents calcium content (mass %) in the composition, P represents phosphorus content (mass %) in the composition, and Mo represents molybdenum content (mass %) in the composition.