Lubricating Oil Composition

Abstract

A crankcase lubricating oil composition comprising: (A) an oil of lubricating viscosity in a major amount; (B) as an additive component in a minor amount, an oil-soluble metal salt of a dithiophosphoric acid; (C) as an additive component in a minor amount, an oil-soluble carbodiimide compound; and, wherein the lubricating oil composition is contaminated with at least 0.3 mass %, based on the total mass of the lubricating oil composition, of a biofuel or a decomposition product thereof and mixtures thereof.

1  A crankcase lubricating oil composition comprising:
 (A) an oil of lubricating viscosity in a major amount; 
 (B) as an additive component in a minor amount, an oil-soluble metal salt of a dithiophosphoric acid; and 
 (C) as an additive component in a minor amount, an oil-soluble carbodiimide compound; and, 
 
       wherein the lubricating oil composition is contaminated with at least 0.3 mass %, based on the total mass of the lubricating oil composition, of a biofuel or a decomposition product thereof and mixtures thereof. 
     
     
         2 . The lubricating oil composition as claimed in  claim 1 , wherein the oil-soluble metal salt of a dithiophosphoric acid comprises a zinc salt of a dithiophosphoric acid. 
     
     
         3 . The lubricating oil composition as claimed in  claim 1 , wherein the oil-soluble carbodiimide compound comprises a mono-carbodiimide of general formula (I):
   R 3 —N═C═N—R 4    (I)
   
       wherein:
 R 3  and R 4  each independently represent hydrogen or a hydrocarbyl group, which group is optionally terminated or substituted with one or more nitrogen and/or oxygen and/or halogen containing substituents and/or interrupted by one or more oxygen and/or nitrogen atoms. 
 
     
     
         4 . The lubricating oil composition as claimed in  claim 3 , wherein each of R 3  and R 4  are identical. 
     
     
         5 . The lubricating oil composition as claimed in  claim 1 , further including (D) an oil-soluble metal deactivator as an additive in a minor amount. 
     
     
         6 . The lubricating oil composition as claimed in  claim 5 , wherein the metal deactivator comprises a compound containing a triazole ring, a compound containing a thiadiazole ring or a compound containing a mercaptobenzimidazole ring. 
     
     
         7 . The lubricating oil composition as claimed in  claim 1 , further comprising one or more co-additives in a minor amount, other than additive components (B) and (C), and (D) if present, selected from ashless dispersants, metal detergents, corrosion inhibitors, antioxidants, pour point depressants, antiwear agents, friction modifiers, demulsifiers, antifoam agents and viscosity modifiers. 
     
     
         8 . A method of lubricating a compression-ignited or spark-ignited internal combustion engine which is fuelled at least in part with a biofuel, which method comprises operating the engine with a crankcase lubricating oil composition as claimed in  claim 1 . 
     
     
         9 . A method of reducing and/or inhibiting the corrosion of the metallic engine components in a compression-ignited or spark-ignited internal combustion engine which is fuelled at least in part with a biofuel, which method comprises operating the engine with a crankcase lubricating oil composition as claimed in  claim 1 . 
     
     
         10 . The method as claimed in  claim 9 , wherein said metallic engine components are non-ferrous metallic engine components. 
     
     
         11 . The method as claimed in  claim 10 , wherein said non-ferrous metallic engine components are components comprising lead, copper or mixtures thereof. 
     
     
         12 . The method as claimed in  claim 12 , wherein said non-ferrous metallic engine components comprise lead. 
     
     
         13 . The method as claimed in  claim 8 , wherein the engine comprises a compression-ignited internal combustion engine which is fuelled at least in part with a biodiesel fuel. 
     
     
         14 . The method as claimed in  claim 9 , wherein the engine comprises a compression-ignited internal combustion engine which is fuelled at least in part with a biodiesel fuel. 
     
     
         15 . A spark-ignited or compression-ignited internal combustion engine comprising a crankcase containing a lubricating oil composition as claimed in  claim 1 , wherein the engine is fuelled at least in part with a biofuel. 
     
     
         16 . An engine as claimed in  claim 15 , wherein the engine is operating with the fuel comprising said biofuel and the engine is lubricated with said lubricating oil composition.