Engine flush process and composition

Abstract

An internal combustion engine can be cleaned of sludge, deposits, or wear debris, by supplying to lubricated surfaces of said engine a composition having a kinematic viscosity of 1 to 10 mm 2 /s at 100° C. comprising oil having at least 15% aromatics by ASTM D-2007; at least 2.5 weight percent of a nitrogen-containing dispersant; at least 0.6 weight percent of an overbased metal detergent; and at least about 0.5 weight percent of a metal salt of a phosphorus acid, circulating the composition through the engine and removing the composition from the engine.

1 . A method for removing at least a portion of at least one of sludge, deposits, and wear debris from the lubricated surfaces of an internal combustion engine which has accumulated such sludge, deposits, or wear debris, comprising: 
 (a) supplying to lubricated surfaces of said engine a composition having a kinematic viscosity of about 1 to about 9.3 mm 2 /s at 100° C. and a flash point of at least about 125° C., comprising 
 (i) oil having at least about 15% aromatics by ASTM D-2007;  
 (ii) at least about 2.5 weight percent of a nitrogen-containing dispersant; and  
 (iii) at least about 0.6 weight percent of an overbased metal detergent;  
   (b) circulating said composition through the engine; and    (c) removing said composition from the engine.    
   
   
       2 . The method of  claim 1  wherein the composition is circulated through the engine by means of running the engine.  
   
   
       3 . The method of  claim 1  wherein the composition is circulated through the engine by means of an external pump.  
   
   
       4 . The method of  claim 1  wherein the composition is circulated through the engine for about 1 minute to about 1 hour.  
   
   
       5 . The method of  claim 1  wherein the composition is circulated at a temperature of about 20 to about 130° C.  
   
   
       6 . The method of  claim 1  wherein the oil is an API Group I base stock.  
   
   
       7 . The method of  claim 1  wherein the oil has a viscosity of about 0.5 to about 7.5 mm 2 /s at 100° C.  
   
   
       8 . The method of  claim 1  wherein the dispersant is a succinimide dispersant.  
   
   
       9 . The method of  claim 8  wherein the succinimide dispersant has a TBN of less than about 45 and a TAN of greater than about 4, on an oil-free basis.  
   
   
       10 . The method of  claim 1  wherein the overbased metal detergent comprises a calcium, magnesium, or sodium sulfonate, phenate, salicylate, salixarate, or saligenin, or mixtures thereof.  
   
   
       11 . The method of  claim 1  wherein the overbased metal detergent comprises a sodium sulfonate.  
   
   
       12 . The method of  claim 1  wherein the overbased metal detergent component has a TBN of about 100 to about 800.  
   
   
       13 . The method of  claim 1  wherein the composition further comprises (iv) at least about 0.5 weight percent of a metal salt of a phosphorus acid.  
   
   
       14 . The method of  claim 13  wherein the metal salt of a phosphorus acid is a zinc dihydrocarbyldithiophosphate.  
   
   
       15 . The method of  claim 1  wherein the composition further comprises a seal swell agent.  
   
   
       16 . The method of  claim 1  wherein the composition further comprises at least one additional additive selected from the group consisting of antioxidants, organic borate esters, and pour point depressants.  
   
   
       17 . The method of  claim 1  wherein the composition comprises 0 to about 0.4% polymeric viscosity modifier.  
   
   
       18 . The method of  claim 1  wherein the composition is substantially free from polymeric viscosity modifier.  
   
   
       19 . The method of  claim 1  wherein the composition is substantially free from solvent having a flash point of less than 93° C.  
   
   
       20 . The method of  claim 1  wherein the engine is a gasoline fueled engine or a light duty diesel engine.  
   
   
       21 . A composition having a kinematic viscosity of about 1 to about 9.3 mm 2 /s at 100° C. and a flash point of at least about 125° C., comprising 
 (a) oil having at least about 15% aromatics by ASTM D-2007;    (b) at least about 2.5 weight percent of a succinimide dispersant; and    (c) at least about 0.6 weight percent of an overbased metal detergent.