Lubricating oil composition

Abstract

The present invention provides a lubricating oil composition which has excellent anti-wear properties for a metal pulley and a metal belt and initial anti-shudder properties and can retain the anti-shudder properties for a long period of time, suitable for use in a continuously variable transmission with a slip-controlled wet clutch and a metal belt. The lubricating oil composition comprises a lubricating base oil, (A) an alkylsalicylic acid metal salt and/or an (overbased) basic salt thereof, wherein the component ratio of the monoalkylsalicylic acid metal salt is from 85 to 100 percent by mole, the component ratio of the dialkylsalicylic acid metal salt is from 0 to 15 percent by mole and the component ratio of the 3-alkylsalicylic acid metal salt is from 40 to 100 percent by mole; (B) a specific nitrogen compound; and (C) a phosphorus-containing anti-wear agent.

1 . A lubricating oil composition suitable for a transmission with a slip-controlled wet clutch, comprising:
 a lubricating base oil;   (A) an alkylsalicylic acid metal salt and/or an (overbased) basic salt thereof, wherein the component ratio of the monoalkylsalicylic acid metal salt is from 85 to 100 percent by mole, the component ratio of the dialkylsalicylic acid metal salt is from 0 to 15 percent by mole and the component ratio of the 3-alkylsalicylic acid metal salt is from 40 to 100 percent by mole;   (B) a nitrogen compound represented by formula (1) below; and   (C) a phosphorus-containing anti-wear agent:   
       
         
           
           
               
               
           
         
       
       wherein R 1  is a straight-chain or branched alkyl group having 1 to 30 carbon atoms, R 2  is hydrogen or a straight-chain or branched alkyl group having 1 to 24 carbon atoms, and a and b are each independently an integer of 1, 2 or 3. 
     
     
         2 . The lubricating oil composition according to  claim 1 , further comprising a friction modifier.