Lubricating oil compositions

Abstract

The present invention relates to a method of lubricating a passenger car motor vehicle engine having a rotating tappet, comprising lubricating the engine with a lubricating oil composition having up to 0.09 wt % phosphorus, 0.4 wt % sulphur and 1.0 wt % sulphated ash, and being substantially free of friction-modifier.

1 . A method of lubricating an internal combustion engine having a cam and a rotating tappet, the method comprising employing as the lubricant for the engine a lubricating composition comprising a base oil of lubricating viscosity, phosphorus in an amount of from 50 to 900 ppm by mass, sulfur in an amount of from 1500 to 3000 ppm by mass, boron in an amount of from 0.0 to 100 ppm, sulphated ash in an amount not exceeding 1.0 mass %, and friction modifier in an amount of from 0.0 to 0.1 mass %, said amounts being based on the mass of fully formulated lubricating oil composition.  
     
     
         2 . The method of  claim 1  wherein the lubricating oil composition comprises less than 0.05 mass % friction modifier, based on the mass of fully formulated oil composition.  
     
     
         3 . The method of  claim 1 , wherein any friction modifier in the lubricating compositions is selected from one or more of the following: glycerol esters of fatty acids, nitrogen-containing friction modifiers and molybdenum compounds.  
     
     
         4 . The method of  claim 1 , wherein sulphated ash of the lubricating oil composition amounts to less than 0.7 mass %.  
     
     
         5 . The method of  claim 1 , wherein the phosphorus content of the lubricating oil composition is 0.06 mass % or less, based on the mass of the fully formulated composition.  
     
     
         6 . The method of  claim 1 , wherein the boron content of the composition is less than 90 ppm by mass.  
     
     
         7 . The method of  claim 1 , wherein the lubricating oil composition comprises one or more additives selected from: metal-containing or ash-forming detergents; ashless dispersants; borated ashless dispersants; dihydrocarbyl dithiophosphate metal salts as antiwear and antioxidant agents; oxidation inhibitors or antioxidants; rust or corrosion inhibitors; foam control agents; viscosity stabilizing agents; viscosity modifying agents; pour point depressants; and supplemental antiwear agents.  
     
     
         8 . The method of  claim 1 , wherein the lubricating oil composition comprises one or more nitrogen-containing dispersants, which dispersant(s) provide said composition with from 0.005 to 0.08 mass % of nitrogen.  
     
     
         9 . An internal combustion engine having a rotating tappet lubricated with a lubricating oil composition comprising a base oil of lubricating viscosity; phosphorus in an amount of from 50 to 90 ppm by mass; sulfur in an amount of from 1500 to 3000 ppm by mass; boron in an amount of from 0.0 to 0.1 mass %, sulphated ash in an amount not exceeding 1.0 mass %; and friction modifier in an amount of from 0.0 to 0.1 mass %, said amounts being based on the mass of fully formulated lubricating oil composition.