Lubricating oil composition

Abstract

A lubricating oil composition which may contain a zinc dialkyl dithiophosphate, and whose color deterioration over time is alleviated. Such a lubricating oil composition may contain: a base oil (A); a zinc dialkyl dithiophosphate (B); and a sodium-based detergent (C). In such a lubricating oil composition, a content of zinc atoms may be 100 ppm by mass to 2,000 ppm by mass based on a total amount of the lubricating oil composition, and a content of sodium atoms may be 5 ppm by mass to 1,000 ppm by mass based on the total amount of the lubricating oil composition.

1 . A lubricating oil composition, comprising:
 a base oil (A);   a zinc dialkyl dithiophosphate (B); and   a sodium-based detergent (C),   wherein a content of zinc atoms is 100 ppm by mass to 2,000 ppm by mass based on a total amount of the lubricating oil composition, and   wherein a content of sodium atoms is 5 ppm by mass to 1,000 ppm by mass based on the total amount of the lubricating oil composition.   
     
     
         2 . The composition of  claim 1 , wherein a content ratio [(Zn)/(Na)] of the zinc atoms (Zn) in the lubricating oil composition to the sodium atoms (Na) in the lubricating oil composition is 0.050 to 50 in terms of a mass ratio. 
     
     
         3 . The composition of  claim 1 , wherein a content of magnesium atoms is less than 30 ppm by mass based on the total amount of the composition. 
     
     
         4 . The composition of  claim 1 , wherein a content of calcium atoms is less than 30 ppm by mass based on the total amount of the composition. 
     
     
         5 . The composition of  claim 1 , wherein an ASTM color after a copper piece and an iron piece are put as catalysts and an ISOT test in conformity with JIS K2514-1:2013 is performed at 150° C. for 168 hours is 1.0 or less. 
     
     
         6 . The composition of  claim 1 , wherein the base oil (A) has a kinematic viscosity at 40° C. of 9.00 mm 2 /s to 165 mm 2 /s.