Method of lubricating an internal combustion engine

Abstract

The invention provides a method of lubricating an end-pivot finger follower valve train lash adjuster of a passenger car compression ignition internal combustion engine having a reference mass not exceeding 2610 kg comprising supplying to the internal combustion engine a lubricating composition comprising an oil of lubricating viscosity 0.01 wt % to 3 wt % of a dispersant viscosity modifier, and 0.01 wt % to 3 wt % of a zinc free sulphur-containing antiwear agent, wherein the lubricating composition has a sulphur-content of less than 5000 ppm, a phosphorus content of 1000 ppm or less, and a sulphated ash content of (typically 3000 to 12,000 ppm).

1 - 22 . (canceled) 
     
     
         23 . A method of lubricating an end-pivot finger follower valve train lash adjuster of a passenger car compression ignition internal combustion engine having a reference mass not exceeding 2610 kg comprising supplying to the internal combustion engine a lubricating composition comprising an oil of lubricating viscosity 0.01 wt % to 3 wt % of a dispersant viscosity modifier, and 0.01 wt % to 3 wt % of a zinc free sulphur-containing antiwear agent, wherein the lubricating composition has a sulphur-content of less than 5000 ppm, a phosphorus content of 1000 ppm or less, and a sulphated ash content of 3000 to 12,000 ppm. 
     
     
         24 . The method of  claim 23 , wherein the lubricating composition has a sulphur-content of 500 to 4000 ppm, a phosphorus content of 300 to 900 ppm, and a sulphated ash content of 3000 to 7000 ppm. 
     
     
         25 . The method of  claim 23 , wherein the dispersant viscosity modifier is an olefin copolymer further functionalised with a dispersant amine group, wherein the olefin copolymer is an ethylene-propylene copolymer. 
     
     
         26 . The method of  claim 25 , wherein the olefin copolymer has a number average molecular weight of 8000 to 45,000. 
     
     
         27 . The method of  claim 25 , wherein the dispersant amine group is derived from reacting the olefin copolymer with an acylating agent and an aromatic amine having a primary or secondary amino group. 
     
     
         28 . The method of  claim 23 , wherein the dispersant viscosity modifier is present at 0.05 wt % to 1.5 wt %, or 0.1 wt % to 1 wt %, or 0.1 to 0.5 wt %. 
     
     
         29 . The method of  claim 23 , wherein the zinc free sulphur-containing antiwear agent is selected from the group consisting of a sulphurised olefin, molybdenum dithiocarbamate, molybdenum dithiophosphate, an amine salt of a (thio)phosphorus-containing compound, a thiadiazole, and mixtures thereof. 
     
     
         30 . The method  claim 29 , wherein the sulphurised olefin is an ester-containing sulphurised olefin. 
     
     
         31 . The method of  claim 30 , wherein the sulphurised olefin is a sulphurised 4-carbobutoxy cyclohexene. 
     
     
         32 . The method of  claim 23 , wherein the zinc free sulphur-containing antiwear agent is present at 0.01 wt % to 1.5 wt. 
     
     
         33 . The method of  claim 23 , wherein the lubricating composition comprises zinc free sulphur-containing antiwear agent comprising 0.01 wt % to 1.5 wt % sulphurised olefin, and 0.05 wt % to 1.5 wt %, an olefin copolymer further functionalised with a dispersant amine group, wherein the olefin copolymer is an ethylene-propylene copolymer. 
     
     
         34 . The method of  claim 23 , wherein the lubricating composition comprises a zinc free sulphur-containing antiwear agent comprising 0.1 to 0.5 wt % sulphurised olefin, and 0.1 to 0.5 wt % of an olefin copolymer further functionalised with a dispersant amine group, wherein the olefin copolymer is an ethylene-propylene copolymer. 
     
     
         35 . The method of  claim 23 , wherein the lubricating composition further comprises an antioxidant, 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 %. 
     
     
         36 . The method of  claim 23 , wherein the lubricating composition further comprises a calcium sulphonate overbased detergent and a calcium phenate overbased detergent in an amount such that the sulphated ash content is 1000 ppm or less. 
     
     
         37 . The method of  claim 36 , wherein the calcium sulphonate overbased detergent is present at 0.01 to 0.5 wt %, or 0.05 to 0.3 wt % of the lubricating composition. 
     
     
         38 . The method of  claim 23 , wherein the lash adjuster comprises a ball and socket joint. 
     
     
         39 . The method of  claim 23 , wherein the lash adjuster is a hydraulic lash adjuster.