Lubricating Oil Composition

Abstract

A crankcase lubricating oil composition comprising (A) an oil of lubricating viscosity; and (B) as an additive component one or more oil-soluble organic acid anhydrides, the or each anhydride carrying at least one linear (unbranched) aliphatic hydrocarbyl substituent having 12 to 36 carbon atoms.

1 . A crankcase lubricating oil composition comprising or made by admixing
 (A) an oil of lubricating viscosity; and   (B) as an additive component, one or more oil-soluble organic acid anhydride, the or each anhydride carrying at least one linear unbranched aliphatic hydrocarbyl substituent having 12 to 36, such as 12 to 24, carbon atoms.   
     
     
         2 . A composition as claimed in  claim 1  where the or each hydrocarbyl substituent is a saturated or double-bond unsaturated hydrocarbyl group. 
     
     
         3 . A composition as claimed in  claim 2  where the hydrocarbyl substituent is an alkyl group. 
     
     
         4 . A composition as claimed in  claim 1  where the acid anhydride is succinic anhydride. 
     
     
         5 . A composition as claimed in  claim 4  where the succinic anhydride has the formula: 
       
         
           
           
               
               
           
         
         where R is a linear unbranched aliphatic hydrocarbyl substituent having 12 to 36 carbon atoms. 
       
     
     
         6 . A composition as claimed in  claim 5  wherein R is an alkyl group. 
     
     
         7 . A composition as claimed in  claim 1  where the or each aliphatic hydrocarbyl group is n-octadecyl. 
     
     
         8 . A composition as claimed in  claim 1  where the oil of lubricating viscosity is present in a concentrate-forming amount. 
     
     
         9 . A composition as claimed in  claim 8  further including one or more other additive components, different from (B). 
     
     
         10 . A composition as claimed in  claim 1  in the form of a lubricant where the oil of lubricating viscosity is present in a major amount and (B), and any other additive components, are present in respective minor amounts. 
     
     
         11 . A composition as claimed in  claim 10  where the other additives, different from (B), are selected from one or more ashless dispersants, metal detergents, corrosion inhibitors, antioxidants, pour point depressants, antiwear agents, friction modifiers, demulsifiers, antifoam and viscosity modifiers. 
     
     
         12 . A method of enabling a passenger car motor oil composition to achieve a reduced boundary friction coefficient when the oil is fresh and to retain that boundary friction performance under oxidative conditions, which method comprises providing the composition with minor amounts of one or more additives (B) as defined in  claim 1 . 
     
     
         13 . A method of lubricating surfaces of an internal combustion engine during its operation comprising:
 (i) providing, in a minor amount, one or more additives (B) as defined in  claim 1  in a major amount of an oil of lubricating viscosity to make a lubricant, to improve the friction modifying properties of the lubricant;   (ii) providing the lubricant to the crankcase of the internal combustion engine;   (iii) providing a hydrocarbon fuel in the combustion chamber of the engine; and   (iv) combusting the fuel in the combustion chamber.