Additive Package for Marine Engine Lubrication

Abstract

An additive package for a two- or four-stroke marine engine lubricant comprises an oil of lubricating viscosity, a salicylate detergent and a sulfonate detergent in a ratio of 90/10 to 10/90 (expressed as mmol of soap), and 1 to 10 mass % of a hydrocarbylphenol-aldehyde condensate.

What is claimed is: 
     
         1 . An additive package for a two-stroke or four-stroke marine engine lubricating oil composition, comprising an oil of lubricating viscosity in a minor amount; a major amount of (A) an overbased metal hydroxybenzoate detergent additive and (B) an overbased metal sulfonate detergent additive; and (C) an oil-soluble hydrocarbylphenol-aldehyde condensate additive in an amount in the range of 1 to 10 mass %; wherein the ratio of (A) to (B), expressed as mmol of soap, is in the range of 90:10 to 10:90. 
     
     
         2 . A two-stroke or four-stroke marine engine lubricating oil composition comprising an oil of lubricating viscosity in a major amount, blended with a minor amount of the additive package claimed in  claim 1 ; wherein the composition, when a two-stroke engine composition, has a TBN of 10 to 120 mg KOH/g, as measured using ASTM D2896; and, when a four-stroke engine composition, has a TBN of 25 to 60 mg KOH/g, as measured using ASTM D2896. 
     
     
         3 . The additive package of  claim 1 , where (A) is an overbased calcium salicylate detergent. 
     
     
         4 . The composition of  claim 2 , where (A) is an overbased calcium salicylate detergent. 
     
     
         5 . The additive package of  claims 1 , where (B) is an overbased calcium sulfonate detergent. 
     
     
         6 . The composition of  claim 2 , where (B) is an overbased calcium sulfonate detergent. 
     
     
         7 . The additive package of  claim 1 , where (C) is a methylene-bridged alkylphenol, the hydroxyl groups of which are either capped or uncapped. 
     
     
         8 . The composition of  claim 2 , where (C) is a methylene-bridged alkyiphenol, the hydroxyl groups of which are either capped or uncapped. 
     
     
         9 . The composition of  claim 2  in the form of a marine diesel cylinder lubricant. 
     
     
         10 . A method of lubricating a cross-head marine diesel engine comprising supplying a composition of  claim 2  to the piston/cylinder of the engine during its operation.