Marine engine lubrication

Abstract

Marine engine (two- or four-stroke) lubrication is effected by a composition comprising a major amount of an oil of lubricating viscosity blended with minor amounts of one or more additives and a star polymer or olefin co-polymer viscosity modifier dispersed in a heavy basestock diluent oil.

What is claimed is: 
     
         1 . A two-stroke or four-stroke marine engine lubricating oil composition comprising an oil of lubricating viscosity in a major amount, and blended with:
 (A) one or more additives, in respective minor amounts; and   (B) a viscosity modifier in the form of either (i) a polymer comprising a core and a plurality of polymeric arms extending therefrom, or (ii) an olefin copolymer, the viscosity modifier being dispersed in a diluent oil having a kinematic viscosity at 100° C. in the range of 6-15 mm 2  s 1 ,   wherein the two-stoke marine engine lubricating oil composition has a TBN of 10 to 100 mg KOH/g, as measured using ASTM D2896 and the four-stroke marine engine lubricating oil composition has a TBN of 25 to 60 mg KOH/g, as measured using ASTM D2896.   
     
     
         2 . A method of making a two-stroke or four-stroke marine engine lubricating oil composition comprising blending an oil of lubricating viscosity in a major amount with:
 (A) one or more additives, in relative minor amounts; and   (B) a viscosity modifier in the form of either (i) a polymer comprising a core and a plurality of polymeric arms extending therefrom, or (ii) an olefin copolymer, the viscosity modifier being dispersed in a diluent oil of kinematic viscosity at 100° C. in the range of 6-15 mm 2  s −1 ,   wherein the two-stoke marine engine lubricating oil composition has a TBN of 10 to 100 mg KOH/g, as measured using ASTM D2896 and the four-stroke marine engine lubricating oil composition has a TBN of 25 to 60 mg KOH/g, as measured using ASTM D2896.   
     
     
         3 . A two-stroke or four-stroke marine engine lubricating oil composition obtained or obtainable by the method of  claim 2 . 
     
     
         4 . The composition of  claim 1 , wherein the composition contains less than 0.5 mass % of brightstock. 
     
     
         5 . The composition of  claim 4 , wherein the composition is completely or substantially free of brightstock. 
     
     
         6 . The method of  claim 2 , wherein the composition contains less than 0.5 mass % of brightstock. 
     
     
         7 . The method of  claim 6 , wherein the composition is completely or substantially free of brightstock. 
     
     
         8 . The composition of  claim 1 , wherein the viscosity modifier (B) is present in the composition in an amount in the range of 0.01 to 40 mass %. 
     
     
         9 . The composition of  claim 8 , wherein the viscosity modifier (B) comprises the polymer (i), the arms of which comprise a hydrogenated isoprene-butadiene copolymer, a hydrogenated styrene-isoprene-butadiene copolymer, a hydrogenated isoprene-styrene copolymer or a hydrogenated butadiene-styrene copolymer. 
     
     
         10 . The composition  claim 8 , wherein the viscosity modifier (B) comprises the olefin copolymer (ii) as a copolymer of two or more monomers of C 2 -C 30  olefins, such as a copolymer of ethylene with a C 3 -C 30  olefin such as propylene. 
     
     
         11 . The method of  claim 2 , wherein the viscosity modifier (B) is present in the composition in an amount in the range of 0.01 to 40 mass %. 
     
     
         12 . The method of  claim 11 , wherein the viscosity modifier (B) comprises the polymer (i), the arms of which comprise a hydrogenated isoprene-butadiene copolymer, a hydrogenated styrene-isoprene-butadiene copolymer, a hydrogenated isoprene-styrene copolymer or a hydrogenated butadiene-styrene copolymer. 
     
     
         13 . The method of  claim 11 , wherein the viscosity modifier (B) comprises the olefin copolymer (ii) as a copolymer of two or more monomers of C 2 -C 30  olefins, such as a copolymer of ethylene with a C 3 -C 30  olefin such as propylene. 
     
     
         14 . The composition of  claim 1 , wherein the composition is in the form of a marine diesel cylinder lubricant. 
     
     
         15 . The composition of  claim 1 , wherein the composition is in the form of a trunk piston engine oil. 
     
     
         16 . The method of  claim 2 , wherein the composition is in the form of a marine diesel cylinder lubricant. 
     
     
         17 . The method of  claim 2 , wherein the composition is in the form of a trunk piston engine oil. 
     
     
         18 . A method of lubricating a cross-head marine diesel engine comprising supplying a composition of  claim 1  to the piston/cylinder of the engine. 
     
     
         19 . A method of lubricating a trunk piston marine diesel engine comprising supplying a composition of  claim 1  to the engine. 
     
     
         20 . The composition of  claim 1 , wherein the oil of lubricating viscosity contains 50% or more of a basestock that contains greater than or equal to 90% saturates and less than or equal to 0.03% sulphur. 
     
     
         21 . The method of  claim 2 , wherein the oil of lubricating viscosity contains 50% or more of a basestock that contains less than 90 percent saturates and/or greater than 0.03% sulphur. 
     
     
         22 . The method of  claim 18 , wherein the oil of lubricating viscosity contains 50% or more of a basestock that contains less than 90 percent saturates and/or greater than 0.03% sulphur. 
     
     
         23 . The method of  claim 19 , wherein the oil of lubricating viscosity contains 50% or more of a basestock that contains less than 90 percent saturates and/or greater than 0.03% sulphur.