Heavy duty diesel engine lubricating oil compositions

Abstract

The use of an effective amount of one or more compounds capable of reducing friction coefficients under mixed lubrication or boundary lubrication conditions in a heavy duty diesel engine lubricating oil composition for improving the fuel economy of a heavy duty diesel engine.

What is claimed is:  
     
         1 . A method composition for improving the fuel economy of a heavy duty diesel engine, which method comprises lubricating said engine with a lubricating oil composition comprising an effective amount of one or more compounds capable of reducing friction coefficients under mixed lubrication or boundary lubrication conditions in a heavy duty diesel engine lubricating oil composition.  
     
     
         2 . The method of  claim 1  wherein the heavy duty diesel engine is the engine of a land-based vehicle, has a total displacement of at least 6.5 litres and a displacement per cylinder of at least 1.0 litre per cylinder.  
     
     
         3 . A heavy duty diesel engine lubricating oil composition comprising an oil of lubricating viscosity, in a major amount, and added thereto: 
 (A) an effective amount of one or more compounds capable of reducing friction coefficients under mixed lubrication or boundary lubrication conditions;    (B) a minor amount of a detergent composition comprising a metal salt of an aromatic carboxylic acid; and    (C) a minor amount of a dispersant additive;    provided that the lubricating oil composition has a nitrogen content of at least 0.06 mass %, based on the mass of the composition.    
     
     
         4 . The oil composition of  claim 3 , wherein the oil composition satisfies at least the API CG-4 performance specification and/or the ACEA E2-96 performance specification.  
     
     
         5 . The oil composition of  claim 3  in the form of an SAE 5W-X or SAE 0W-X lubricating oil composition, where X is any one of 20, 30, 40 and 50.  
     
     
         6 . The oil composition of  claim 4  in the form of an SAE 5W-X or SAE 0W-X lubricating oil composition, where X is any one of 20, 30, 40 and 50.  
     
     
         7 . The oil composition of  claim 3  wherein the base blend viscosity of the composition is at least 8.2 mm 2 s −1  at 100° C.  
     
     
         8 . The oil composition of  claim 4  wherein the base blend viscosity of the composition is at least 8.2 mm 2 s −1  at 100° C.  
     
     
         9 . The oil composition of  claim 5  wherein the base blend viscosity of the composition is at least 8.2 mm 2 s −1  at 100° C.  
     
     
         10 . The oil composition of  claim 3  wherein the or at least one of the compounds has a polar head-group and an oleophilic hydrocarbyl chain.  
     
     
         11 . The oil composition of  claim 4  wherein the or at least one of the compounds has a polar head-group and an oleophilic hydrocarbyl chain.  
     
     
         12 . The oil composition of  claim 5  wherein the or at least one of the compounds has a polar head-group and an oleophilic hydrocarbyl chain.  
     
     
         13 . The oil composition of  claim 3  wherein the or at least one of the compounds is a molybdenum compound.  
     
     
         14 . The oil composition of  claim 4  wherein the or at least one of the compounds is a molybdenum compound.  
     
     
         15 . The oil composition of  claim 5  wherein the or at least one of the compounds is a molybdenum compound.  
     
     
         16 . A heavy duty diesel engine additive concentrate composition comprising a diluent and one or more additives comprising: 
 (A) one or more compounds capable of reducing friction coefficients under mixed lubrication or boundary lubrication conditions;    (B) a detergent composition comprising a metal salt of an aromatic carboxylic acid; and    (C) a dispersant additive;    each in such a proportion as to provide a heavy duty diesel engine lubricating oil composition as defined in  claim 3  when the oil composition contains 2 to 20 mass % of the additives.    
     
     
         17 . A combination of a heavy duty diesel engine in a land-based vehicle, which engine has a total displacement of at least 6.5 litres and a displacement per cylinder of at least 1.0 litre per cylinder and a lubricating oil composition as defined in  claim 3.