Lubricating oil composition for diesel engines

Abstract

Lubricating oil composition for use in diesel engines which comprises, in the base oil, not more than 0.3% by mass of sulphated ash, from 0.01 to 0.2% by mass of nitrogen in succinimides, from 0.05 to 0.12% by mass of zinc in zinc dithiophosphates, from 0.02 to 0.3% by mass of nitrogen in amine-based anti-oxidants, and from 0.01 to 0.08% by mass of boron, which further has a total value of [(zinc amount in zinc dithiophosphates)×(nitrogen amount in succinimides)] and [(zinc amount in zinc dithiophosphates)×(nitrogen amount in amine-based anti-oxidants)] as regards the aforementioned of from 0.015 to 0.06, and which does not contain salicylate, phenate or sulphonate metallic detergents. The intention is to obtain a lubricating oil composition for use in diesel engines which does not contain a metallic detergent yet maintains excellent engine (piston) detergency while preventing DPF clogging, and which reduces valve-train wear.

1 . A lubricating oil composition for use in diesel engines which comprises, in the base oil, not more than 0.3% by mass of sulphated ash, from 0.01 to 0.2% by mass of nitrogen in succinimides, from 0.05 to 0.12% by mass of zinc in zinc dithiophosphates, from 0.02 to 0.3% by mass of nitrogen in amine-based anti-oxidants, and from 0.01 to 0.08% by mass of boron, which further has a total value of [(zinc amount in zinc dithiophosphates)×(nitrogen amount in succinimides)] and [(zinc amount in zinc dithiophosphates)×(nitrogen amount in amine-based anti-oxidants)] in an amount of not less than 0.015, and which does not contain salicylate, phenate or sulphonate metallic detergents. 
     
     
         2 . The lubricating oil composition according to  claim 1  wherein the base oil is a single base oil or a mixture selected from Group II, Group III, Group IV and Group V, and where the sulphur component of the base oil is not more than 50 ppm. 
     
     
         3 . The lubricating oil composition according to  claim 1  having a Top Groove fill according to Japanese Automobile Standards Organization M336:1998 Detergency Test Procedure of not more than 30%, and cam nose wear according to Japanese Automobile Standards Organization M354:1999 Valve-train Wear Test Procedure of not more than 95 μm. 
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein the base oil contains secondary alkyl zinc dithiophosphates, wherein the alkyl groups have from 3 to 12 carbon atoms.