Lubricant composition

Abstract

A lubricating oil composition may be capable of satisfactorily exhibiting sludge prevention properties and wear resistance evaluated by scoring resistance and seizure resistance over a long period of time. Such a lubricating oil composition may contain: a base oil (A); a hindered phenol-based antioxidant (B); one or more imide compounds (C) selected from the group consisting of a monoimide compound (C1) and a bisimide compound (C2); and an extreme pressure agent (D), in which the hindered phenol-based antioxidant (B) is 2,6-di-tert-butylphenol, the monoimide compound (C1) is one or more selected from the group consisting of an alkenyl succinic monoimide compound and an alkyl succinic monoimide compound, and the bisimide compound (C2) is one or more selected from the group consisting of an alkenyl succinic bisimide compound and an alkyl succinic bisimide compound.

1 . A lubricating oil composition, comprising:
 a base oil (A);   a hindered phenol-based antioxidant (B);   one or more imide compounds (C) selected from the group consisting of a monoimide compound (C1) and a bisimide compound (C2); and   an extreme pressure agent (D),   wherein the hindered phenol-based antioxidant (B) is 2,6-di-tert-butylphenol,   wherein the monoimide compound (C1) is one or more selected from the group consisting of an alkenyl succinic monoimide compound and an alkyl succinic monoimide compound, and   wherein the bisimide compound (C2) is one or more selected from the group consisting of an alkenyl succinic bisimide compound and an alkyl succinic bisimide compound.   
     
     
         2 . The composition of  claim 1 , further comprising:
 an amine-based antioxidant (E).   
     
     
         3 . The composition of  claim 2 , wherein a content ratio [(B)/(E)] of the hindered phenol-based antioxidant (B) to the amine-based antioxidant (E) is 6/1 to 10/1 in terms of a mass ratio. 
     
     
         4 . The composition of  claim 1 , wherein a content ratio [(C1)/(C2)] of the monoimide compound (C1) to the bisimide compound (C2) is more than 0 and 2/1 or less in terms of a mass ratio. 
     
     
         5 . The composition of  claim 1 , wherein a content of 2,6-di-tert-butyl-p-cresol is less than 0.60% by mass based on a total amount of the lubricating oil composition. 
     
     
         6 . The composition of  claim 1 , wherein the extreme pressure agent (D) is one or more selected from the group consisting of a phosphorus-based extreme pressure agent (D1) and a sulfur-phosphorus-based extreme pressure agent (D2). 
     
     
         7 . The composition of  claim 1 , further comprising:
 a sorbitan fatty acid ester (F).   
     
     
         8 . The composition of  claim 1 , which is used as a hydraulic oil.