Methods for improving resistance to timing chain wear with a multi-component detergent system

Abstract

A method for reducing timing chain stretch in an engine comprising a step of lubricating said timing chain with a lubricating oil composition that includes a major amount of a base oil; and a minor amount of an additive package including at least one overbased calcium phenate detergent having a total base number of at least 150 mg KOH/g, measured by the method of ASTM D-2896, at least one calcium sulfonate detergent; and at least one magnesium-containing detergent. The lubricating oil composition has a weight ratio of total calcium from the at least one calcium sulfonate detergent to total calcium and magnesium in the lubricating oil composition of from about 0.06 to less than about 0.45.

1 . A method for reducing timing chain stretch of a timing chain in an engine comprising a step of lubricating said timing chain with a lubricating oil composition comprising:
 a major amount of a base oil; and   a minor amount of an additive package including:
 a) at least one overbased calcium phenate detergent having a total base number of at least 150 mg KOH/g, measured by the method of ASTM D-2896; 
 b) at least one calcium sulfonate detergent; and 
 c) at least one magnesium-containing detergent; 
   
       wherein the lubricating oil composition has a weight ratio of total calcium from the at least one calcium sulfonate detergent to total calcium and magnesium in the lubricating oil composition of from 0.06 to 0.35. 
     
     
         2 . The method according to  claim 1 , wherein the at least one magnesium-containing detergent is overbased having a total base number of at least 225 mg KOH/g, measured by the method of ASTM D-2896. 
     
     
         3 . The method according to  claim 1 , wherein the at least one magnesium-containing detergent is selected from an overbased magnesium phenate, overbased magnesium sulfur containing phenates, overbased magnesium sulfonates, overbased magnesium calixarates, overbased magnesium salixarates, overbased magnesium salicylates, overbased magnesium carboxylic acids, overbased magnesium phosphorus acids, overbased magnesium mono- and/or di-thiophosphoric acids, overbased magnesium alkyl phenols, overbased magnesium sulfur coupled alkyl phenol compounds, overbased magnesium methylene bridged phenols and combinations thereof. 
     
     
         4 . The method according to  claim 1 , wherein the at least one calcium sulfonate detergent is overbased having a total base number of at least 225 mg KOH/g, measured by the method of ASTM D-2896. 
     
     
         5 . (canceled) 
     
     
         6 . The method of  claim 1 , wherein the additive package further comprises one or more additives selected from the group consisting of antioxidants, friction modifiers, pour point depressants, and viscosity index improvers. 
     
     
         7 . The method of  claim 6 , wherein the antioxidant is an oil soluble molybdenum complex. 
     
     
         8 . The method of  claim 1 , wherein the base oil has viscosity grade of 5W-X or 0W-X and the lubricating oil composition comprises one or more antioxidants selected from an aromatic amine, an alkylated diphenylamine, a phenyl-alpha-naphthylamine, and an alkylated phenyl-alpha-naphthylamine. 
     
     
         9 . The method of  claim 1 , wherein the lubricating oil composition contains from about 50 ppm to about 1650 ppm of calcium provided by the at least one calcium sulfonate detergent, based on a total weight of the lubricating oil composition. 
     
     
         10 . The method of  claim 1 , wherein the lubricating oil composition contains from about 100 ppm to about 2000 ppm of calcium provided by the at least one calcium phenate detergent, based on a total weight of the lubricating oil composition. 
     
     
         11 . The method of  claim 1 , wherein the lubricating oil composition contains from about 400 ppm to about 2200 ppm of calcium provided by all of the overbased calcium-containing detergents, based on a total weight of the lubricating oil composition. 
     
     
         12 . The method of  claim 1 , wherein the total amount of calcium in the lubricating oil composition is from about 1000 ppm to less than about 3090 ppm. 
     
     
         13 . The method of  claim 1 , wherein the lubricating oil composition contains from about 50 ppm to about 1650 ppm of magnesium provided by the at least one magnesium-containing detergent, based on a total weight of the lubricating oil composition. 
     
     
         14 . The method of  claim 1 , wherein the lubricating oil composition contains a total of from about 500 ppm to less than 3100 ppm of magnesium and calcium, based on a total weight of the lubricating oil composition. 
     
     
         15 . The method of  claim 1 , wherein the lubricating oil composition further comprises a metal dialkyl dithiophosphate. 
     
     
         16 . The method of  claim 1 , wherein the engine is a spark ignition engine. 
     
     
         17 . The method of  claim 1 , wherein the engine is a spark ignition passenger car gasoline engine. 
     
     
         18 . The method of  claim 1 , wherein the lubricating oil composition is capable of reducing the timing chain stretch in an engine to 0.1% or less, as measured by the Ford Chain Wear Test over 216 hours.