Composition and method for preventing or reducing engine knock and pre-ignition in high compression spark ignition engines

Abstract

A method for preventing or reducing engine knock or pre-ignition in a high compression spark ignition engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition that contains (i) a lubricating oil base stock comprising at least one branched ester having at least about 15% of the total carbons in the form of methyl groups, and (ii) at least one ashless antiwear additive selected from a phosphorus-containing ashless antiwear additive, a sulfur-containing ashless antiwear additive, and a phosphorus/sulfur-containing ashless antiwear additive. A lubricating engine oil having a composition that contains (i) a lubricating oil base stock comprising at least one branched ester having at least about 15% of the total carbons in the form of methyl groups, and (ii) at least one ashless antiwear additive selected from a phosphorus-containing ashless antiwear additive, a sulfur-containing ashless antiwear additive, and a phosphorus/sulfur-containing ashless antiwear additive. The lubricating oils of this disclosure are useful as passenger vehicle engine oil (PVEO) products.

What is claimed is: 
     
         1 . A method for preventing or reducing engine knock or pre-ignition in a high compression spark ignition engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil, said formulated oil having a composition comprising (i) a lubricating oil base stock comprising at least one branched ester having at least 15% of the total carbons in the form of methyl groups, and (ii) at least one ashless antiwear additive selected from the group consisting of a phosphorus-containing ashless antiwear additive, a sulfur-containing ashless antiwear additive, and a phosphorus/sulfur-containing ashless antiwear additive. 
     
     
         2 . The method of  claim 1  wherein the formulated oil is an ashless formulated oil. 
     
     
         3 . The method of  claim 1  wherein the lubricating oil base stock comprises at least one branched polyol ester having at least 30% of the total carbons in the form of methyl groups. 
     
     
         4 . The method of  claim 1  wherein the at least one ashless antiwear additive comprises an amine phosphate, a thiophosphate, a dithiophosphate, an amine salt of sulfurized phosphate, an alkylated triphenylphosphorothionate, or mixtures thereof. 
     
     
         5 . The method of  claim 1  wherein the formulated oil further comprises an aminic antioxidant. 
     
     
         6 . The method of  claim 1  wherein the formulated oil further comprises a polymeric aminic antioxidant. 
     
     
         7 . The method of  claim 1  wherein the formulated oil, when 5% of the formulated oil is added to isooctane, the resulting isooctane/formulated oil mixture maintains at least 80% of the isooctane ignition delay or combustion delay using the equipment and test conditions of ASTM D7668. 
     
     
         8 . The method of  claim 1  wherein the at least one branched ester is present in an amount of from 1 to 99.8 weight percent, based on the total weight of the formulated oil, and the at least one ashless antiwear additive is present in an amount from 0.1 to 4 weight percent, based on the total weight of the formulated oil. 
     
     
         9 . The method of  claim 1  wherein the formulated oil further comprises at least one dialkyl adipic acid ester having at least 25% of the total alkyl carbons in the form methyl groups. 
     
     
         10 . The method of  claim 9  wherein the dialkyl adipic acid ester is selected from the group consisting of diisopropyl adipate, diisobutyl adipate, diisopentyl adipate, diisohexyl adipate, diisooctyl adipate, diisononyl adipate, diisodecyl adipate, and mixtures thereof. 
     
     
         11 . The method of  claim 1  wherein the formulated oil further comprises at least one branched polyol ester having at least 40% of the total carbons in the form of methyl groups. 
     
     
         12 . The method of  claim 1  wherein the lubricating oil further comprises one or more of a detergent, dispersant, viscosity index improver, antioxidant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, anti-rust additive, and friction modifier. 
     
     
         13 . The method of  claim 12  wherein the detergent is an ashless nonionic detergent. 
     
     
         14 . The method of  claim 1  wherein the high compression spark ignition engine has a compression ratio of at least 12. 
     
     
         15 . The method of  claim 1  wherein the high compression spark ignition engine is a super-charged engine or a turbo-charged engine. 
     
     
         16 . The method of  claim 1  wherein the pre-ignition is low speed pre-ignition (LSPI). 
     
     
         17 . The method of  claim 3  wherein the at least one branched polyol ester is derived from at least one polyhydric alcohol and at least one branched mono-carboxylic acid. 
     
     
         18 . The method of  claim 17  wherein the polyhydric alcohol is selected from the group consisting of neopentyl glycol, 2,2-dimethylol butane, trimethylol ethane, trimethylol propane, trimethylol butane, mono-pentaerythritol, di-pentaerythritol, tri-pentaerythritol, ethylene glycol, propylene glycol and polyalkylene glycols, and mixtures thereof. 
     
     
         19 . The method of  claim 17  wherein the branched mono-carboxylic acid is selected from the group consisting of 2,2-dimethyl propionic acid (neopentanoic acid), neoheptanoic acid, neooctanoic acid, neononanoic acid, iso-hexanoic acid, neodecanoic acid, 2-ethyl hexanoic acid (2EH), 3,5,5-trimethyl hexanoic acid (TMH), isoheptanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, and mixtures thereof. 
     
     
         20 . The method of  claim 17  wherein the at least one branched polyol ester of at least one branched mono-carboxylic acid comprises a mono-pentaerythritol ester of at least one branched mono-carboxylic acid or, a di-pentaerythritol ester of at least one branched mono-carboxylic acid. 
     
     
         21 . A lubricating engine oil for high compression spark ignition engines having a composition comprising (i) a lubricating oil base stock comprising at least one branched ester having at least 15% of the total carbons in the form of methyl groups, and (ii) at least one ashless antiwear additive selected from the group consisting of a phosphorus-containing ashless antiwear additive, a sulfur-containing ashless antiwear additive, and a phosphorus/sulfur-containing ashless antiwear additive; wherein when 5% of the lubricating engine oil is added to isooctane, the resulting isooctane/lubricating engine oil mixture maintains at least 80% of the isooctane ignition delay or combustion delay, using the equipment and test conditions of ASTM D7668. 
     
     
         22 . The lubricating engine oil for high compression spark ignition engines of  claim 21  which is an ashless lubricating engine oil. 
     
     
         23 . The lubricating engine oil for high compression spark ignition engines of  claim 21  wherein the lubricating oil base stock comprises at least one branched polyol ester having at least 30% of the total carbons in the form of methyl groups. 
     
     
         24 . The lubricating engine oil for high compression spark ignition engines of  claim 21  wherein the at least one ashless antiwear additive comprises an amine phosphate, a thiophosphate, a dithiophosphate, an amine salt of sulfurized phosphate, an alkylated triphenylphosphorothionate, or mixtures thereof. 
     
     
         25 . The lubricating engine oil for high compression spark ignition engines of  claim 21  further comprising an aminic antioxidant. 
     
     
         26 . The lubricating engine oil for high compression spark ignition engines of  claim 21  further comprising a polymeric aminic antioxidant. 
     
     
         27 . The lubricating engine oil for high compression spark ignition engines of  claim 21  wherein the at least one branched ester is present in an amount of from 1 to 99.8 weight percent, based on the total weight of the formulated oil, and the at least one ashless antiwear additive is present in an amount from 0.1 to 4 weight percent, based on the total weight of the formulated oil. 
     
     
         28 . The lubricating engine oil for high compression spark ignition engines of  claim 21  which further comprises at least one dialkyl adipic acid ester having at least 25% of the total alkyl carbons in the form methyl groups. 
     
     
         29 . The lubricating engine oil for high compression spark ignition engines of  claim 28  wherein the dialkyl adipic acid ester is selected from the group consisting of diisopropyl adipate, diisobutyl adipate, diisopentyl adipate, diisohexyl adipate, diisooctyl adipate, diisononyl adipate, diisodecyl adipate, and mixtures thereof. 
     
     
         30 . The lubricating engine oil for high compression spark ignition engines of  claim 21  which further comprises one or more of a detergent, dispersant, viscosity index improver, antioxidant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, anti-rust additive, and friction modifier. 
     
     
         31 . The lubricating engine oil for high compression spark ignition engines of  claim 30  wherein the detergent is an ashless nonionic detergent. 
     
     
         32 . The lubricating engine oil for high compression spark ignition engines of  claim 21  wherein the high compression spark ignition engine has a compression ratio of at least 13. 
     
     
         33 . The lubricating engine oil for high compression spark ignition engines of  claim 21  wherein the high compression spark ignition engine is a super-charged engine or a turbo-charged engine. 
     
     
         34 . The lubricating engine oil for high compression spark ignition engines of  claim 21  wherein the pre-ignition is low speed pre-ignition (LSPI). 
     
     
         35 . The lubricating engine oil for high compression spark ignition engines of  claim 23  wherein the at least one branched polyol ester is derived from at least one polyhydric alcohol and at least one branched mono-carboxylic acid. 
     
     
         36 . The lubricating engine oil for high compression spark ignition engines of  claim 35  wherein the polyhydric alcohol is selected from the group consisting of neopentyl glycol, 2,2-dimethylol butane, trimethylol ethane, trimethylol propane, trimethylol butane, mono-pentaerythritol, pentaerythritol, di-pentaerythritol, tri-pentaerythritol, ethylene glycol, propylene glycol and polyalkylene glycols, and mixtures thereof. 
     
     
         37 . The lubricating engine oil for high compression spark ignition engines of  claim 35  wherein the branched mono-carboxylic acid is selected from the group consisting of 2,2-dimethyl propionic acid (neopentanoic acid), neoheptanoic acid, neooctanoic acid, neononanoic acid, iso-hexanoic acid, neodecanoic acid, 2-ethyl hexanoic acid (2EH), 3,5,5-trimethyl hexanoic acid (TMH), isoheptanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, and mixtures thereof. 
     
     
         38 . The lubricating engine oil for high compression spark ignition engines of  claim 35  wherein the at least one branched polyol ester of at least one branched mono-carboxylic acid comprises a mono-pentaerythritol ester of at least one branched mono-carboxylic acid or a di-pentaerythritol ester of at least one branched mono-carboxylic acid. 
     
     
         39 . A method of making a lubricating engine oil for high compression spark ignition engines, said method comprising blending a lubricating oil base stock comprising at least one branched ester having at least 15% of the total carbons in the form of methyl groups, with at least one ashless antiwear additive selected from the group consisting of a phosphorus-containing ashless antiwear additive, a sulfur-containing ashless antiwear additive, and a phosphorus/sulfur-containing ashless antiwear additive, in an amount sufficient that, when 5% of the lubricating engine oil is added to isooctane, the resulting isooctane/lubricating engine oil mixture maintains at least 80% of the isooctane ignition delay or combustion delay, using the equipment and test conditions of ASTM D7668. 
     
     
         40 . A high compression spark ignition engine lubricated with the lubricating engine oil of  claim 21 . 
     
     
         41 . A method for preventing or reducing engine knock or pre-ignition in a natural gas spark ignition engine lubricated with a lubricating oil by using the lubricating engine oil of  claim 21 . 
     
     
         42 . A method for preventing or reducing engine knock or pre-ignition in a high compression spark ignition engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil, said formulated oil having a composition comprising (i) a lubricating oil base stock comprising at least one mono-pentaerythritol ester of a branched mono-carboxylic acid having at least 30% of the total carbons in the form of methyl groups, or di-pentaerythritol ester of a branched mono-carboxylic acid having at least 30% of the total carbons in the form of methyl groups, and (ii) at least one ashless antiwear additive selected from the group consisting of an amine phosphate, a thiophosphate, a dithiophosphate, an amine salt of sulfurized phosphate, an alkylate phosphorothionate, or mixtures thereof. 
     
     
         43 . The method of  claim 42  wherein the formulated oil further comprises an alkylated phenyl naphthylamine antioxidant. 
     
     
         44 . A lubricating engine oil for high compression spark ignition engines having a composition comprising (i) a lubricating oil base stock comprising at least one mono-pentaerythritol ester of a branched mono-carboxylic acid having at least 30% of the total carbons in the form of methyl groups, or di-pentaerythritol ester of a branched mono-carboxylic acid having at least 30% of the total carbons in the form of methyl groups, and (ii) at least one ashless antiwear additive selected from the group consisting of an amine phosphate, a thiophosphate, a dithiophosphate, an amine salt of sulfurized phosphate, an alkylated phosphorothionate, or mixtures thereof; wherein when 5% of the lubricating engine oil is added to isooctane, the resulting isooctane/lubricating engine oil mixture maintains at least 80% of the isooctane ignition delay or combustion delay, using the equipment and test conditions of ASTM D7668. 
     
     
         45 . The lubricating engine oil for high compression spark ignition engines of  claim 44  further comprising an alkylated phenyl naphthylamine antioxidant.