Lubricating oil composition

Abstract

A low sulphated ash lubricating oil composition comprising an overbased magnesium salicylate detergent and an ashless alkylene bis(dihydrocarbyldithiocarbamate) which exhibits an extended drain interval.

What is claimed is: 
     
         1 . A lubricating oil composition having a sulphated ash content of less than or equal to 1.0 mass % as determined by ASTM D874, the composition comprising or made by admixing:
 (A) an oil of lubricating viscosity in a major amount;   (B) one or more oil-soluble or oil-dispersible overbased magnesium salicylate detergent(s) having a TBN of greater than or equal to 220 mg/g KOH as determined by ASTM D2896, as an additive in a minor amount; and,   (C) an oil-soluble or oil-dispersible ashless alkylene bis(dihydrocarbyldithiocarbamate), as an additive in a minor amount.   
     
     
         2 . A lubricating oil composition as claimed in  claim 1 , wherein the ashless alkylene bis(dihydrocarbyldithiocarbamate) is a compound of formula (I): 
       
         
           
           
               
               
           
         
         wherein: 
         R 1 , R 2 , R 3  and R 4  each independently represent, at each occurrence when used herein, a C 1  to C 30  hydrocarbyl group; and, 
         X represents a C 1  to C 20  alkylene group. 
       
     
     
         3 . A lubricating oil composition as claimed in  claim 2 , wherein R 1 , R 2 , R 3  and R 4  each independently represent a linear or branched C 1  to C 16  alkyl group. 
     
     
         4 . A lubricating oil composition as claimed in  claim 2 , wherein R 1 , R 2 , R 3  and R 4  each independently represent a C 1  to C 16  alkyl substituted phenyl group or an unsubstituted phenyl group. 
     
     
         5 . A lubricating oil composition as claimed in  claim 2 , wherein R 1 , R 2 , R 3  and R 4  are identical. 
     
     
         6 . A lubricating oil composition as claimed in  claim 2 , wherein R 1  and R 3  each independently represent a branched or linear C 1  to C 16  alkyl group and R 2  and R 4  each independently represent a C 1  to C 16  alkyl substituted phenyl group or an unsubstituted phenyl group 
     
     
         7 . A lubricating oil composition as claimed in  claim 2 , wherein X represents a methylene group. 
     
     
         8 . A lubricating oil composition as claimed in  claim 1 , wherein the ashless alkylene bis(dihydrocarbyldithiocarbamate) is methylene bis(dibutyldithiocarbamate). 
     
     
         9 . A lubricating oil composition as claimed in  claim 1 , wherein the one or more overbased magnesium salicylate detergent(s) provides the lubricating oil composition with greater than or equal to 0.05 mass % of magnesium (ASTM D5185), based on the total mass of the lubricating oil composition. 
     
     
         10 . A lubricating oil composition as claimed in  claim 1 , wherein the one or more overbased magnesium salicylate detergent(s) are the sole metal containing detergent(s) which are present in the lubricating oil composition. 
     
     
         11 . A lubricating oil composition as claimed in  claim 1 , wherein the lubricating oil composition further includes at least 0.05 mass %, based on the total mass of the lubricating oil composition, of an aminic anti-oxidant, a phenolic anti-oxidant or a combination thereof. 
     
     
         12 . A lubricating oil composition as claimed in  claim 1 , wherein the lubricating oil composition further includes an oil-soluble or oil-dispersible organo-molybdenum compound which provides the lubricating oil composition with at least 10 ppm of molybdenum (ASTM D5185), based on the total mass of the lubricating oil composition. 
     
     
         13 . A method of lubricating a spark-ignited or compression-ignited internal combustion engine comprising lubricating the engine with a lubricating oil composition as claimed in  claim 1 .