Lubricant composition for bio-diesel fuel engine applications

Abstract

A diesel engine operating on a fuel containing from about 5 to about 100 wt. % bio-diesel components and being lubricated with a lubricating oil composition including a major amount of oil of lubricating viscosity, and a minor amount of at least one highly grafted, multi-functional olefin copolymer. The olefin copolymer is made by reacting an acylating agent with an olefin copolymer having a number average molecular weight greater than about 1,000 in the present of a free radical initiator to provide an acylated olefin copolymer having a degree of grafting (DOG) of the acylating agent on the olefin copolymer of at least 0.5 wt. %, and reacting the acylated olefin copolymer with an amine to provide the highly grafted, multi-functional olefin copolymer. As used, the highly grafted, multi-functional olefin copolymer is effective to reduce a viscosity increase in the lubricating oil composition for the engine.

1 . A diesel engine operating on a fuel containing from about 5 to about 100 wt. % bio-diesel components and being lubricated with a lubricating oil composition comprising a major amount of oil of lubricating viscosity, and a minor amount of at least one highly grafted, multi-functional olefin copolymer made by reacting an acylating agent with an olefin copolymer having a number average molecular weight greater than about 1,000 in the presence of a free radical initiator to provide an acylated olefin copolymer having a degree of grafting (DOG) of the acylating agent on the olefin copolymer of at least 0.5 wt. %, and reacting the acylated olefin copolymer with an amine to provide the highly grafted, multi-functional olefin copolymer, wherein the highly grafted, multi-functional olefin copolymer is effective to reduce a viscosity increase in the lubricating oil composition for the engine to less than or equal to a viscosity increase in a lubrication oil composition for an engine operating on a fuel devoid of the bio-diesel components. 
     
     
         2 . The diesel engine of  claim 1 , wherein the oil of lubricating viscosity has a saturates content of at least 75 wt. %, and the olefin copolymer comprises a copolymer of ethylene and one or more C 3 -C 23  alpha olefins. 
     
     
         3 . The diesel engine of  claim 1 , wherein the lubricating oil composition further comprises a dispersant/inhibitor package. 
     
     
         4 . The diesel engine of  claim 3 , wherein the dispersant/inhibitor package comprises a dispersant, a metal-containing detergent, an antiwear agent, an antioxidant, and a friction modifier. 
     
     
         5 . The diesel engine of  claim 4 , wherein the detergent is selected from the group consisting of neutral and overbased calcium sulfonate, overbased magnesium sulfonate, calcium phenate, calcium salicylate, magnesium salicylate, magnesium phenate, and mixtures thereof. 
     
     
         6 . The diesel engine of  claim 4 , wherein the dispersant comprises one or more polyalkenyl succinimide dispersants. 
     
     
         7 . The diesel engine of  claim 4 , wherein the friction modifier is selected from the group consisting of non-metal containing organic friction modifiers, organometallic friction modifiers, and mixtures thereof. 
     
     
         8 . The diesel engine of  claim 7 , wherein the organometallic friction modifier is selected from the group consisting of oil soluble organo-titanium, oil soluble organo-molybdenum compounds, and oil soluble organo-tungsten compounds. 
     
     
         9 . The diesel engine of  claim 7 , wherein the non-metal containing friction modifier is selected from the group consisting of glycerol monooleate, and nitrogen containing friction modifiers. 
     
     
         10 . The diesel engine of  claim 1 , wherein the acylated olefin copolymer has a degree of grafting (DOG) ranging from about 1.5 to about 2.5 wt. %. 
     
     
         11 . The diesel engine of  claim 1 , wherein the diesel engine is equipped with an exhaust gas recirculation system. 
     
     
         12 . A method for reducing a viscosity increase in a lubricating oil composition for a diesel engine operating on a fuel containing from about 5 to about 100 wt. % bio-diesel, comprising:
 lubricating the engine with a lubricant composition comprising a major amount of oil of lubricating viscosity, and a minor amount of at least one highly grafted, multi-functional olefin copolymer made by reacting an acylating agent with an olefin copolymer having a number average molecular weight greater than about 1,000 in the present of a free radical initiator to provide an acylated olefin copolymer having a degree of grafting (DOG) of the acylating agent on the olefin copolymer of at least 0.5 wt. %, and reacting the acylated olefin copolymer with an amine to provide the highly grafted, multi-functional olefin copolymer, and   operating the engine to provide a viscosity increase as determined by a T-11 engine test in the lubricating oil composition that is less than a viscosity increase in the lubricating oil for an engine operating on a diesel fuel devoid of bio-diesel components.   
     
     
         13 . The method of  claim 12 , wherein the diesel engine comprises a diesel engine having an exhaust gas recirculation system. 
     
     
         14 . The method of  claim 12 , wherein the lubricant composition has a saturates content of at least 75 wt. %, and the olefin copolymer comprises a copolymer of ethylene and one or more C 3 -C 23  alpha olefins. 
     
     
         15 . The method of  claim 14 , wherein the lubricant composition further comprises a dispersant/inhibitor package. 
     
     
         16 . The method of  claim 15 , wherein the dispersant/inhibitor package comprises a dispersant, a metal-containing detergent, an antiwear agent, an antioxidant, and a friction modifier. 
     
     
         17 . The method of  claim 16 , wherein the detergent is selected from the group consisting of neutral and overbased calcium sulfonate, overbased magnesium sulfonate, calcium phenate, calcium salicylate, magnesium salicylate, magnesium phenate, and mixtures thereof. 
     
     
         18 . The method of  claim 16 , wherein the dispersant comprises one or more polyalkenyl succinimide dispersants. 
     
     
         19 . The method of  claim 16 , wherein the friction modifier is selected from the group consisting of non-metal containing organic friction modifiers, organometallic friction modifiers, and mixtures thereof. 
     
     
         20 . The method of  claim 19 , wherein the organometallic friction modifier is selected from the group consisting of oil soluble organo-titanium, oil soluble organo-molybdenum compounds, and oil soluble organo-tungsten compounds. 
     
     
         21 . The method of  claim 19 , wherein the non-metal containing friction modifier is selected from the group consisting of glycerol monooleate, and nitrogen-containing friction modifiers. 
     
     
         22 . The method of  claim 12 , wherein the acylated olefin copolymer has a degree of grafting (DOG) ranging from about 1.5 to about 2.5 wt. %.