Reduced engine deposits from dispersant treated with cobalt

Abstract

The invention provides a lubricating composition containing an oil of lubricating viscosity and a dispersant treated with cobalt reagent. The invention further relates to methods of lubricating an internal combustion engine by supplying the described lubricating composition to the internal combustion engine. The invention further relates to the use of a dispersant treated with cobalt to reduce deposits on the inner surfaces of engine components.

What is claimed: 
     
         1 . An internal combustion engine lubricant composition comprising;
 a) an oil of lubricating viscosity,   b) about 0.5 to 10 wt. % of a metal substituted dispersant based on the weight of said engine oil lubricant composition,   c) an antioxidant,   d) an antiwear additive,   
       wherein the metal of the metal dispersant comprises cobalt and the amount of metal substituted dispersant is such to provide about 40 to 500 ppm of cobalt to said engine lubricant composition and wherein the lubricant composition comprises sulfur in an amount of less than 1 wt. % and phosphorus in an amount of less than 0.2 wt. % based on the weight of said lubricant composition. 
     
     
         2 . A composition according to  claim 1 , wherein said metal substituted dispersant is present from about 1 to about 6 wt. % of said lubricant composition. 
     
     
         3 . A composition according to  claim 1 , wherein said cobalt is present from about 50 to about 300 ppm in said engine lubricant composition. 
     
     
         4 . A composition according to  claim 1 , wherein said cobalt is present from about 80 to about 250 ppm in said engine lubricant composition. 
     
     
         5 . A composition according to  claim 1 , wherein said metal substituted dispersant is present from about 1.5 to about 3.5 wt. % in said engine lubricant composition. 
     
     
         6 . A composition according to  claim 1 , wherein said metal substituted dispersant is a metal substituted succinimide dispersant. 
     
     
         7 . A composition according to  claim 1 , further comprising an overbased detergent. 
     
     
         8 . A composition according to  claim 1 , wherein said antioxidant comprises an aminic antioxidant and/or a phenolic antioxidant. 
     
     
         9 . A composition according to  claim 8 , wherein said aminic antioxidant is present in an amount from about 0.1 to about 10 wt. % based on said lubricant composition. 
     
     
         10 . A composition according to  claim 8 , wherein said phenolic antioxidant is present in an amount from about 0.1 to about 10 wt. % based on said lubricant composition. 
     
     
         11 . A composition according to any of  claim 1 , wherein said anti-wear agent is a metal dithiophosphate antiwear agent. 
     
     
         12 . A composition according to  claim 1 , wherein the lubricant composition comprises sulfur in an amount of less than 0.8 wt. % and phosphorus in an amount of less than 0.1 wt. % based on the weight of said lubricant composition. 
     
     
         13 . A composition according to  claim 1 , wherein the lubricant composition comprises molybdenum in an amount of less than 100 parts per million parts in weight/weight (ppm), and boron in the amount of less than 100 ppm, all based on the weight of the lubricant composition. 
     
     
         14 . A method of using an ashless dispersant reacted with a cobalt compound as an additive in a lubricating composition to reduce engine deposits when said lubricant is exposed to use at temperatures of 150° C. or more and wherein said ashless dispersant reacted with a cobalt compound is used in an amount to provide about 40 to 500 ppm of cobalt to said lubricating composition and wherein the lubricating composition comprises sulfur in an amount of less than 1 wt. % and phosphorus in an amount of less than 0.2 wt. % based on the weight of said lubricating composition. 
     
     
         15 . A method of using an ashless dispersant according to  claim 4 , wherein said lubricant is exposed to use at temperatures of 200° C. or more.