Lubricating oil compositions and method for preventing or reducing low speed pre-ignition in direct injected spark-ignited engines

Abstract

A lubricant composition for a direct injected, boosted, spark ignited internal combustion engine that contains at least one potassium and/or lithium-containing compound is disclosed. This disclosure also relates to a method for preventing or reducing low speed pre-ignition in an engine lubricated with a formulated oil. The formulated oil has a composition comprising at least one oil soluble or oil dispersible potassium and/or lithium compound.

What is claimed is: 
     
         1 . A method for preventing or reducing low speed pre-ignition in a direct injected, boosted, spark ignited internal combustion engine, said method comprising the step of lubricating the crankcase of the engine with a lubricating oil composition comprising from about 300 to about 3500 ppm of metal from at least one potassium-containing compound, based on the total weight of the lubricating oil. 
     
     
         2 . The method of  claim 1 , wherein the engine is operated under a load with a break mean effective pressure (BMEP) of from about 12 to about 30 bars. 
     
     
         3 . The method of  claim 1 , wherein the engine is operated at speeds between 500 and 3,000 rpm. 
     
     
         4 . The method of  claim 1 , wherein the potassium-containing compound is a potassium-containing detergent. 
     
     
         5 . The method of  claim 4 , wherein the detergent comprises one or more of a sulfonate detergent, a phenate detergent, a carboxylate detergent, a salicylate detergent, or combinations thereof 
     
     
         6 . The method of  claim 1 , wherein the lubricant composition further comprises at least one other additive selected from an ashless dispersant, an ashless antioxidant, a phosphorus- containing anti-wear additive, a friction modifier, and a polymeric viscosity modifier. 
     
     
         7 . The method of any one of  claims 1  to  6 , wherein there is a reduction in the number of LSPI events of at least 50 percent, at least 60 percent, at least 70 percent, at least 80 percent, at least 90 percent, at least 95 percent. 
     
     
         8 . The method of any one of  claims 1  to  7 , wherein the low speed pre-ignition events are reduced to less than 10 LSPI events per 100,000 combustion events. 
     
     
         9 . The method of any one of  claims 1  to  8 , wherein the low speed pre-ignition events are reduced to less than 5 LSPI events per 100,000 combustion events. 
     
     
         10 . A lubricating engine oil composition for a direct injected, boosted, spark ignited internal combustion engine comprising from about 300 to about 3500 ppm of metal from at least one potassium-containing compound, based on the total weight of the lubricating oil. 
     
     
         11 . A lubricating engine oil composition comprising a lubricating oil base stock as a major component; and at least one potassium-containing compound, as a minor component; and wherein the engine exhibits greater than 50% reduced low speed pre-ignition, based on normalized low speed pre-ignition (LSPI) counts per 100,000 engine cycles, engine operation at between 500 and 3,000 revolutions per minute and brake mean effective pressure (BMEP) between 10 and 30 bar, as compared to low speed pre-ignition performance achieved in an engine using a lubricating oil that does not comprise the at least one potassium-containing compound. 
     
     
         12 . The lubricating engine oil composition according to  claim 11 , wherein the amount of metal from the potassium-containing compound is from about 300 to about 3500 ppm, based on the total weight of the lubricating oil. 
     
     
         13 . Use of a at least one potassium-containing compound for preventing or reducing low speed pre-ignition in a direct injected, boosted, spark ignited internal combustion engine. 
     
     
         14 . Use of  claim 13 , wherein the at least one potassium-containing compound is present in from about 300 to about 3500 ppm of metal from the at least one potassium-containing compound, based on the total weight of the lubricating oil. 
     
     
         15 . A method for preventing or reducing low speed pre-ignition in a direct injected, boosted, spark ignited internal combustion engine, said method comprising the step of lubricating the crankcase of the engine with a lubricating oil composition comprising from about 100 to about 900 ppm of metal from at least one lithium-containing compound, based on the total weight of the lubricating oil. 
     
     
         16 . The method of  claim 15 , wherein the engine is operated under a load with a break mean effective pressure (BMEP) of from about 12 to about 30 bars. 
     
     
         17 . The method of  claim 15 , wherein the engine is operated at speeds between 500 and 3,000 rpm. 
     
     
         18 . The method of  claim 15 , wherein the lithium-containing compound is a lithium- containing detergent. 
     
     
         19 . The method of  claim 18 , wherein the detergent comprises one or more of a sulfonate detergent, a phenate detergent, a carboxylate detergent, a salicylate detergent, or combinations thereof 
     
     
         20 . The method of  claim 15 , wherein the lubricant composition further comprises at least one other additive selected from an ashless dispersant, an ashless antioxidant, a phosphorus- containing anti-wear additive, a friction modifier, and a polymeric viscosity modifier. 
     
     
         21 . The method of any one of  claims 15  to  20 , wherein there is a reduction in the number of LSPI events of at least 50 percent, at least 60 percent, at least 70 percent, at least 80 percent, at least 90 percent, at least 95 percent. 
     
     
         22 . The method of any one of  claims 15  to  21 , wherein the low speed pre-ignition events are reduced to less than 10 LSPI events per 100,000 combustion events. 
     
     
         23 . The method of any one of  claims 15  to  22 , wherein the low speed pre-ignition events are reduced to less than 5 LSPI events per 100,000 combustion events. 
     
     
         24 . A lubricating engine oil composition for a direct injected, boosted, spark ignited internal combustion engine comprising from about 100 to about 900 ppm of metal from at least one lithium-containing compound, based on the total weight of the lubricating oil. 
     
     
         25 . A lubricating engine oil composition comprising a lubricating oil base stock as a major component; and at least one lithium-containing compound, as a minor component; and wherein the engine exhibits greater than 50% reduced low speed pre-ignition, based on normalized low speed pre-ignition (LSPI) counts per 100,000 engine cycles, engine operation at between 500 and 3,000 revolutions per minute and brake mean effective pressure (BMEP) between 10 and 30 bar, as compared to low speed pre-ignition performance achieved in an engine using a lubricating oil that does not comprise the at least one lithium-containing compound. 
     
     
         26 . The lubricating engine oil composition according to  claim 25 , wherein the amount of metal from the lithium-containing compound is from about 300 to 3500 ppm, based on the total weight of the lubricating oil. 
     
     
         27 . Use of a at least one lithium-containing compound for preventing or reducing low speed pre-ignition in a direct injected, boosted, spark ignited internal combustion engine. 
     
     
         28 . Use of  claim 27 , wherein the at least one lithium-containing compound is present in from about 100 to about 900 ppm of metal from the at least one lithium-containing compound, based on the total weight of the lubricating oil.