Marine Diesel Cylinder Lubricants for Fuel Efficiency

Abstract

A lubricant composition comprising an oil of lubricating viscosity and 0.01 to 5 percent by weight of an organic friction modifier, said lubricant composition being substantially free from molybdenum compounds, is suitable for lubricating an internal combustion engine operating at above 150° C. at the cylinder liner, for example, a marine diesel engine.

1 - 14 . (canceled) 
     
     
         15 . A method for lubricating a marine diesel engine operating above 150° C. at the cylinder liner, comprising supplying to the cylinder liner thereof and not to or from a crankcase, a lubricant composition comprising an oil of lubricating viscosity and 0.01 to 5 percent by weight of an organic friction modifier comprising an acid or acid derivative selected from the group consisting of fatty acids; metal salts of fatty acids; fatty acid imidazolines; and hydroxy-carboxylic acid di-esters, di-amides, ester-amides, or imides; said fatty acids containing 6 to 24 carbon atoms; said lubricant composition being substantially free from molybdenum compounds and substantially free from zinc dialkyldithiophosphates. 
     
     
         16 . The method of  claim 15  wherein the organic friction modifier comprises a fatty acid. 
     
     
         17 . The method of  claim 15  wherein the organic friction modifier comprises an imide, di-ester, di-amide, or ester-amide derivative of tartaric acid. 
     
     
         18 . The method of  claim 15  wherein the organic friction modifier comprises oleyl tartrimide. 
     
     
         19 . The method of  claim 15  further comprising 0.1 to 5 percent by weight of a borated dispersant. 
     
     
         20 . The method of  claim 15  further comprising 0.1 to 17 percent by weight of an overbased calcium alkylphenol sulfide detergent. 
     
     
         21 . The method of  claim 15  further comprising 0.5 to 15 percent by weight of an overbased linear alkyl sulfonate detergent having a TBN of 400-900. 
     
     
         22 . The method of  claim 15  wherein the engine is a two-stroke cycle engine. 
     
     
         23 . The method of  claim 15  wherein the lubricant has a TBN of at least about 35. 
     
     
         24 . The method of  claim 15  wherein the lubricant is substantially free from zinc compounds.