Lubricating oil compositions

Abstract

The present invention generally relates to a method for reducing intake valve deposits in a Direct Injection Spark Ignition engine, the method comprising operating the engine with a lubricating oil composition comprising: (a) a major amount of an oil of lubricating viscosity; and (b) at least one foam inhibitor selected from the group consisting of silicon oils, polysiloxanes, polyacrylates, and polymethacrylates; wherein the foam inhibitor is not poly (phenyl-methyl) siloxane; and further wherein the amount of said foam inhibitor in said lubricating oil composition is at an effective concentration to achieve at least 10% reduction in intake valve deposits in said Direct Injection Spark Ignition engine compared to operating the engine with said lubricating oil composition without any foam inhibitor.

1 . A method for reducing intake valve deposits in a Direct Injection Spark Ignition engine, the method comprising operating the engine with a lubricating oil composition comprising:
 (a) a major amount of an oil of lubricating viscosity; and   (b) at least one foam inhibitor selected from the group consisting of silicon oils, polysiloxanes, polyacrylates, and polymethacrylates;   
       wherein the foam inhibitor is not poly (phenyl-methyl) siloxane; and further wherein the amount of said foam inhibitor in said lubricating oil composition is at an effective concentration to achieve at least 10% reduction in intake valve deposits in said Direct Injection Spark Ignition engine compared to operating the engine with said lubricating oil composition without any foam inhibitor. 
     
     
         2 . The method of  claim 1  wherein the foam inhibitor is selected from polysiloxanes and polymethacrylates. 
     
     
         3 . The method of  claim 1  wherein the foam inhibitor is selected from the group consisting of: polydimethyl siloxane, poly (dimethyl, phenyl-methyl) siloxane, poly (trifluoropropylmethyl) siloxane, and a mixture of polydimethyl siloxane and poly (dimethyl, phenyl-methyl) siloxane. 
     
     
         4 . The method of  claim 3  wherein the foam inhibitor is polydimethyl siloxane. 
     
     
         5 . The method of  claim 3  wherein the foam inhibitor is poly (dimethyl, phenyl-methyl) siloxane. 
     
     
         6 . The method of  claim 3  wherein the foam inhibitor is poly (trifluoropropylmethyl) siloxane. 
     
     
         7 . The method of  claim 3  wherein the foam inhibitor is a mixture of polydimethyl siloxane and poly (dimethyl, phenyl-methyl) siloxane. 
     
     
         8 . The method of  claim 1  wherein the concentration of said foam inhibitor in said lubricating oil composition is from about 30 to about 500 ppmw. 
     
     
         9 . The method of  claim 1  wherein the concentration of said foam inhibitor in said lubricating oil composition is from about 100 to about 500 ppmw. 
     
     
         10 . The method of  claim 1  wherein the concentration of said foam inhibitor in said lubricating oil composition is from about 150 to about 500 ppmw. 
     
     
         11 . The method of  claim 1  wherein the concentration of said foam inhibitor in said lubricating oil composition is from about 200 to about 400 ppmw. 
     
     
         12 . The method of  claim 1  wherein the reduction of intake valve deposits is at least 20%. 
     
     
         13 . The method of  claim 1  wherein the reduction of intake valve deposits is at least 30%. 
     
     
         14 . The method of  claim 1  wherein the reduction of intake valve deposits is at least 40%. 
     
     
         15 . The method of  claim 1  wherein the reduction of intake valve deposits is at least 50%. 
     
     
         16 . The method of  claim 1  wherein said lubricating oil composition further comprises at least one additive selected from the group consisting of: detergents, dispersants, antioxidants, ant-wear agents, rust inhibitors, dehazing agents, demulsifying agents, metal deactivating agents, friction modifiers, pour point depressants, co-solvents, package compatibilisers, corrosion inhibitors, dyes, extreme pressure agents, and mixtures thereof. 
     
     
         17 . The method of  claim 1  wherein said oil of lubricating viscosity comprises at least 50 wt-% of an API Group II or a Group III base stock, or mixtures thereof. 
     
     
         18 . A method for reducing intake valve deposits in a Direct Injection Spark Ignition engine, the method comprising:
 (a) operating said engine with a lubricating oil;   (b) top treating said lubricating oil with a lubricating oil concentrate comprising at least one foam inhibitor selected from the group consisting of silicon oils, polysiloxanes, polyacrylates, and polymethacrylates to thereby provide a top treated lubricating oil composition;   
       wherein the foam inhibitor is not poly (phenyl-methyl) siloxane; and further wherein the amount of said foam inhibitor in said top treated lubricating oil composition is at an effective concentration to achieve at least 10% reduction in intake valve deposits in said Direct Injection Spark Ignition engine compared to operating the engine with the lubricating oil in step (a) without any top treatment. 
     
     
         19 . The method of  claim 18  wherein the foam inhibitor is selected from plysiloxanes and polymethacrylates. 
     
     
         20 . The method of  claim 18  wherein the foam inhibitor is selected from the group consisting of: polydimethyl siloxane, poly (dimethyl, phenyl-methyl) siloxane, poly (trifluoropropylmethyl) siloxane, and a mixture of polydimethyl siloxane and poly (dimethyl, phenyl-methyl) siloxane. 
     
     
         21 . The method of  claim 18  wherein the foam inhibitor is polydimethyl siloxane. 
     
     
         22 . The method of  claim 18  wherein the foam inhibitor is poly (dimethyl, phenyl-methyl) siloxane. 
     
     
         23 . The method of  claim 18  wherein the foam inhibitor is poly (trifluoropropylmethyl) siloxane. 
     
     
         24 . The method of  claim 18  wherein the foam inhibitor is a mixture of polydimethyl siloxane and poly (dimethyl, phenyl-methyl) siloxane. 
     
     
         25 . The method of  claim 18  wherein the concentration of said foam inhibitor in said lubricating oil concentrate is from about 0.01 to about 1.0 wt-%. 
     
     
         26 . The method of  claim 18  wherein the concentration of said foam inhibitor in said lubricating oil concentrate is from about 0.02 to about 0.8 wt-%. 
     
     
         27 . The method of  claim 18  wherein the concentration of said foam inhibitor in said lubricating oil concentrate is from about 0.03 to about 0.7 wt-%. 
     
     
         28 . The method of  claim 18  wherein the concentration of said foam inhibitor in said lubricating oil concentrate is from about 0.04 to about 0.6 wt-%. 
     
     
         29 . The method of  claim 18  wherein the final concentration of said foam inhibitor in said top treated lubricating oil composition is from about 30 to about 500 ppmw. 
     
     
         30 . The method of  claim 18  wherein the final concentration of said foam inhibitor in said top treated lubricating oil composition is from about 100 to about 500 ppmw. 
     
     
         31 . The method of  claim 18  wherein the final concentration of said foam inhibitor in said top treated lubricating oil composition is from about 150 to about 500 ppmw. 
     
     
         32 . The method of  claim 18  wherein the final concentration of said foam inhibitor in said top treated lubricating oil composition is from about 200 to about 400 ppmw. 
     
     
         33 . The method of  claim 18  wherein the reduction of intake valve deposits is at least 20%. 
     
     
         34 . The method of  claim 18  wherein the reduction of intake valve deposits is at least 30%. 
     
     
         35 . The method of  claim 18  wherein the reduction of intake valve deposits is at least 40%. 
     
     
         36 . The method of  claim 18  wherein the reduction of intake valve deposits is at least 50%. 
     
     
         37 . The method of  claim 18  wherein said top treated lubricating oil composition further comprises at least one additive selected from the group consisting of: detergents, dispersants, antioxidants, ant-wear agents, rust inhibitors, dehazing agents, demulsifying agents, metal deactivating agents, friction modifiers, pour point depressants, co-solvents, package compatibilisers, corrosion inhibitors, dyes, extreme pressure agents, and mixtures thereof. 
     
     
         38 . The method of  claim 18  wherein said lubricating oil comprises at least 50 wt-% of an API Group II or a Group III base stock, or mixtures thereof.