Lubricating Oil Composition

Abstract

A lubricating oil composition which has a sulfur content of 0.5 wt. % or less and which at least comprises a base oil and the following additive components a) to e): a) an ashless dispersant comprising an alkenyl- or alkyl-succinimide or a derivative thereof; b) an ashless dispersant comprising an alkenyl- or alkyl-succinic ester or a derivative thereof; c) a molybdenum complex of a basic nitrogen-containing compound; d) an alkaline earth metal-containing detergent having TBN of 10-400 mg·KOH/g; and e) an anti-wear agent favorably employed for lubricating internal combustion engines operated using a low sulfur hydrocarbon fuel.

What is claimed is: 
     
         1 . A lubricating oil composition for lubricating internal combustion engines which has a sulfur content of 0.5 wt. % or less and which comprises a base oil having a lubricating viscosity and at least the following additive components a) to e):
 a) an ashless dispersant in an amount of 0.5-5.0 wt. % which comprises an alkenyl- or alkyl-succinimide or a derivative thereof;   b) an ashless dispersant in an amount of 0.5-5.0 wt. % which comprises an alkenyl- or alkyl-succinic ester or a derivative thereof;   c) a molybdenum complex of a basic nitrogen-containing compound in an amount of 50-1,200 wt·ppm in terms of a molybdenum content thereof;   d) an alkaline earth metal-containing detergent having a TBN in the range of 10 to 400 mg·KOH/g in an amount of 0.05-1.0 wt. % in terms of an alkaline earth metal content thereof; and   e) an anti-wear agent in an amount of 0.05-5.0 wt. %.   
     
     
         2 . The lubricating oil composition of  claim 1 , wherein the sulfur content is in the range of 0.01 to 0.2 wt. %. 
     
     
         3 . The lubricating oil composition of  claim 1 , wherein the sulfur content is in the range of 0.05 to 0.12 wt. %. 
     
     
         4 . The lubricating oil composition of  claim 1 , which is a multi-grade engine oil further comprising a viscosity index improver, whereby being classified to 0W5, 0W10, 0W15, 0W20, 0W30, 5W20, 5W30, 10W20, or 10W30. 
     
     
         5 . The lubricating oil composition of  claim 1 , wherein the component a) is contained in an amount of 1.0-4.0 wt. %. 
     
     
         6 . The lubricating oil composition of  claim 1 , wherein the component b) is contained in an amount of 1.0-4.0 wt. %. 
     
     
         7 . The lubricating oil composition of  claim 1 , wherein the ratio of the component a) to the component b) is in the range of 1:4 to 4:1. 
     
     
         8 . The lubricating oil composition of  claim 1 , wherein the component c) contains sulfur not larger than 1 wt. %. 
     
     
         9 . The lubricating oil composition of  claim 1 , wherein the component c) contains sulfur in the range of 0.05 to 0.5 wt. %. 
     
     
         10 . The lubricating oil composition of  claim 1 , wherein the component c) is a molybdenum complex of a succinimide. 
     
     
         11 . The lubricating oil composition of  claim 1 , wherein the component d) comprises an alkaline earth metal salicylate. 
     
     
         12 . The lubricating oil composition of  claim 1 , wherein the anti-wear agent is a zinc dialkyldithiophosphate. 
     
     
         13 . The lubricating oil composition of  claim 1 , which further comprises an oxidation inhibitor. 
     
     
         14 . The lubricating oil composition of  claim 1 , which is employed for lubricating internal combustion engines operated using a fuel oil having a sulfur content of 0.001 wt. % or less. 
     
     
         15 . A method for operating internal engines mounted to land-travelling vehicles using a fuel having a sulfur content of 0.001 wt. % or less under lubrication with the lubricating oil composition of  claim 1 .