Method Of Lubricating An Internal Combustion Engine

Abstract

The disclosed technology provides a method of lubricating a compression-ignition internal combustion engine with a maximum laden mass over 2,700 kg comprising supplying to the engine a lubricating composition comprising: an oil of lubricating viscosity, a 300 TBN or higher alkaline earth metal sulfonate detergent having a metal ratio of 10 to 40, an alkaline earth metal sulfonate detergent having a metal ratio of 3 to 9, and a TBN of 81 to 180 mg KOH/g, wherein the sulfonate detergents provide a total amount of sulfonate substrate of 1 wt % to 3 wt % of the lubricating composition, 0.1 to 1.2 wt % of antioxidant, wherein at least 20 wt % of the antioxidant is a phenolic antioxidant, a borated compound present in an amount to deliver 25 ppm to 300 ppm of boron, the lubricating composition has a sulfated ash content of 0.5 wt % to not more than 1.5 wt %, and the lubricating composition has a TBN of 6.5 to 15 mg KOH/g.

What is claimed is: 
     
         1 . A method of lubricating a compression-ignition internal combustion engine with a maximum laden mass over 2,700 kg comprising supplying to the engine a lubricating composition comprising:
 an oil of lubricating viscosity,   a 300 TBN or higher alkaline earth metal sulfonate detergent having a metal ratio of 9.2 to 40,   an alkaline earth metal sulfonate detergent having a metal ratio of 2.7 to 5, and a TBN of 81 to 180 mg KOH/g (as measured by ASTM D2896-11),   wherein the sulfonate detergents provide a total amount of sulfonate substrate of 1.0 wt % to 3 wt % of the lubricating composition,   0.1 to 1.2 wt % of antioxidant, wherein at least 20 wt % of the antioxidant is a phenolic antioxidant,   a borated compound present in an amount to deliver 75 to 152 ppm of boron and the borated compound is chosen from:
 a borate-ester having the formula:
   (RO) 3 B, 
 
   where each R is independently an alkyl group having 10 to 32 carbon atoms, and
 a borated polyisobutenyl succinimide dispersant derived from a PIB having an Mn of from 1,200 to 2,200, and 
   
       wherein
 the lubricating composition has a sulfated ash content of 0.4 wt % to 1.2 wt % and 
 the lubricating composition has a TBN of 7.5 to 15 mg KOH/g (as measured by ASTM D2896-11). 
 
     
     
         2 . The method of  claim 1 , wherein the lubricating composition is characterized as having (i) a sulfur content of 0.5 wt % or less, and (ii) a phosphorus content of 0.15 wt % or less. 
     
     
         3 . The method of  claim 1 , wherein the oil of lubricating viscosity comprises a base oil selected from one or more of an API Group I, II, III, IV, V, or mixtures thereof. 
     
     
         4 . The method of  claim 1 , wherein the antioxidant comprises an aminic antioxidant. 
     
     
         5 . The method of  claim 4 , wherein the antioxidant comprises at most 60 wt % of the aminic antioxidant. 
     
     
         6 . The method of  claim 1 , wherein the antioxidant comprises a sulfurized olefin antioxidant. 
     
     
         7 . The method of  claim 6 , wherein the antioxidant comprises at most 60 wt % of the sulfurized olefin antioxidant. 
     
     
         8 . The method of  claim 1 , wherein the antioxidant comprises a phenolic or an aminic antioxidant or mixtures thereof, and wherein the antioxidant is present at 0.1 wt % to 3 wt %. 
     
     
         9 . The method of  claim 1 , wherein the lubricating composition has a total base number (TBN) content of 7.5 to 10 mg KOH/g. 
     
     
         10 . The method of  claim 1 , wherein the sulfonate detergents deliver 1.05 to 1.2 wt % of substrate to the lubricating composition. 
     
     
         11 . The method of  claim 1 , wherein the lubricating composition comprises 0 wt % to 0.2 wt % of a phenolic based detergent. 
     
     
         12 . The method of  claim 11 , wherein the lubricating composition comprises 0 wt % of a phenolic based detergent. 
     
     
         13 . The method of  claim 1 , wherein the lubricating composition further comprises a dispersant viscosity modifier. 
     
     
         14 . The method of  claim 13 , wherein the dispersant viscosity modifier is an olefin copolymer further functionalized with a dispersant amine group. 
     
     
         15 . The method of  claim 13 , wherein the dispersant viscosity modifier is prepared by:
 grafting an olefinic carboxylic acid acylating agent onto a polymer of 15 to 80 mole percent of ethylene, from 20 to 85 mole percent of C 3-10  alpha monoolefin, and from 0 to 15 mole percent of non-conjugated diene or triene, said polymer having number average molecular weight ranging from 5000 to 500,000; and   reacting the resultant grafted polymer with an amine.   
     
     
         16 . The method of  claim 1 , wherein the lubricating composition further comprises a non-borated dispersant. 
     
     
         17 . The method of  claim 16 , wherein the non-borated dispersant is an amine-functionalized additive derived from an amine having at least 4 aromatic groups, at least one —NH 2  functional group, and at least 2 secondary or tertiary amino groups. 
     
     
         18 . The method of  claim 1 , wherein the lubricating composition further comprises a zinc dialkyldithiophosphate. 
     
     
         19 . The method of  claim 18 , wherein the zinc dialkyldithiophosphate is a primary zinc dialkyldithiophosphate, or a secondary zinc dialkyldithiophosphate. 
     
     
         20 . The method of  claim 18 , wherein the zinc dialkyldithiophosphate is present to deliver 100 ppm to 1000 ppm of phosphorus. 
     
     
         21 . The method of  claim 1 , wherein the internal combustion engine has a steel surface on a cylinder bore, cylinder block, or piston ring. 
     
     
         22 . The method of  claim 1 , wherein the internal combustion engine has a surface of steel, or an aluminum alloy, or an aluminum composite.