Lubricating Oil Composition

Abstract

A method of passing the ASTM D6557 Ball Rust Test using a lubricating oil composition having a sulfated ash content of less than 1.0% by weight of the composition in which an oil-soluble hydrocarbyl phenol aldehyde condensate rust inhibitor of Formula (I) is added to the lubricating oil composition: wherein n is 0 to 10, Y is a divalent bridging group, and is preferably a hydrocarbyl group, preferably having from 1 to 4 carbon atoms; and R is a hydrocarbyl group having from 4 to 30 carbon atoms.

1 . A method of passing the ASTM D6557 Ball Rust Test using a lubricating oil composition having a sulfated ash content of less than 1.0% by weight of the composition, comprising the addition to an oil of lubricating viscosity of, as a rust inhibitor, an ashless, oil-soluble hydrocarbyl phenol aldehyde condensate represented by general Formula (I),  
       
         
           
           
               
               
           
         
       
       wherein n is 0 to 10, Y is a divalent bridging group; and R is a hydrocarbyl group having from 4 to 30 carbon atoms.  
     
     
         2 . A method according to  claim 1 , wherein Y is a hydrocarbyl group.  
     
     
         3 . A method according to  claim 2 , wherein Y is a hydrocarbyl group having from 1 to 4 carbon atoms;  
     
     
         4 . A method according to  claim 1 , wherein the oil-soluble hydrocarbyl phenol aldehyde condensate has a weight average molecular weight (Mw) of 600 to 4000, as measured by MALDI-TOF (Matrix Assisted Laser Desorption Ionization-Time of Flight) mass spectrometry.  
     
     
         5 . A method according to  claim 4 , wherein said Mw is 800 to 3500.  
     
     
         6 . A method according to  claim 5 , wherein said Mw is 1000 to 2000.  
     
     
         7 . A method according to  claim 6 , wherein said Mw is 1250 to 1680.  
     
     
         8 . A method according to  claim 1 , wherein n is 1 to 8.  
     
     
         9 . A method according to  claim 8 , wherein n is 2 to 6.  
     
     
         10 . A method according to  claim 9 , wherein n 3 to 5.  
     
     
         11 . A method according to  claim 1 , wherein R is a hydrocarbyl group having from 8 to 18 carbon atoms.  
     
     
         12 . A method according to  claim 11 , wherein R is a hydrocarbyl group having from 9 to 15 carbon atoms.  
     
     
         13 . A method according to  claim 1 , wherein the lubricating oil further comprises one or more overbased metal salts of an organic acids, preferably, one or more alkali metal salt or an alkaline earth metal salt of a phenate, sulfonate, salicylate or a complex detergent comprising a combination of any two of an alkali metal salt or an alkaline earth metal salt of a phenate, sulfonate or salicylate.  
     
     
         14 . A method according to  claim 13 , wherein said one or more overbased metal salts of an organic acids are one or more alkali metal salt or an alkaline earth metal salt of a phenate, sulfonate, salicylate or a complex detergent comprising a combination of any two of an alkali metal salt or an alkaline earth metal salt of a phenate, sulfonate or salicylate.