Method for preventing or reducing low speed pre-ignition

Abstract

A method for preventing or reducing low speed pre-ignition in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition including a lubricating oil base stock as a major component, and at least one lubricating oil additive, as a minor component. The lubricating oil contains at least one metal or metalloid in an amount sufficient that, in thermogravimetric measurements of the lubricating oil by a Thermogravimetric Engine Oil Simulation Test, carbon black decomposition temperature is increased as compared to the carbon black decomposition temperature in a lubricating oil containing calcium or magnesium. A lubricating oil useful for preventing or reducing low speed pre-ignition in an engine lubricated with the lubricating oil. The lubricating oils of this disclosure are particularly advantageous as passenger vehicle engine oil (PVEO) products.

1 . A method for preventing or reducing low speed pre-ignition in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil, said formulated oil having a composition comprising a lubricating oil base stock as a major component; and at least one lubricating oil additive, as a minor component; wherein said lubricating oil contains at least one metal or metalloid in an amount sufficient that, in thermogravimetric measurements of the lubricating oil by a Thermogravimetric Engine Oil Simulation Test, carbon black decomposition temperature is increased as compared to the carbon black decomposition temperature in a lubricating oil containing calcium or magnesium. 
     
     
         2 . The method of  claim 1  wherein, in thermogravimetric measurements of the lubricating oil by a Thermogravimetric Engine Oil Simulation Test, the carbon black decomposition temperature is increased by at least 10° C. as compared to the carbon black decomposition temperature in a lubricating oil containing calcium or magnesium. 
     
     
         3 . The method of  claim 1  wherein, in thermogravimetric measurements of the lubricating oil by a Thermogravimetric Engine Oil Simulation Test, the carbon black decomposition temperature is increased by at least 25° C. as compared to the carbon black decomposition temperature in a lubricating oil containing calcium or magnesium. 
     
     
         4 . The method of  claim 1  wherein the engine exhibits greater than about 10% reduced low speed pre-ignition, based on normalized low speed pre-ignition (LSPI) counts per 25,000 engine cycles, engine operation at 2000 revolutions per minute (RPM) and brake mean effective pressure (BMEP) at 18 bar, as compared to low speed pre-ignition performance achieved in an engine using a lubricating oil containing calcium or magnesium. 
     
     
         5 . The method of  claim 1  wherein the at least one metal or metalloid comprises sodium, manganese, titanium, aluminum, or mixtures thereof. 
     
     
         6 . The method of  claim 1  wherein the at least one metal or metalloid is present in the lubricating oil in an amount from about 100 ppm to about 25,000 ppm. 
     
     
         7 . The method of  claim 1  wherein (i) the at least one metal or metalloid is present in the lubricating oil in an amount from about 100 ppm to about 1000 ppm; (ii) total base number (TBN), as measured by ASTM D2896, of the lubricating oil ranges from about 2 mg KOH to about 17 mg KOH; (iii) total sulfated ash of the lubricating oil ranges from about 0.01 to about 1 wt %. 
     
     
         8 . The method of  claim 1  wherein the at least one metal or metalloid is incorporated into the lubricating oil by maintaining constant ash, maintaining constant detergent metal, maintaining constant total base number (TBN), or top treating. 
     
     
         9 . The method of  claim 1  wherein the at least one metal or metalloid is incorporated into the lubricating oil through the at least one lubricating oil additive. 
     
     
         10 . The method of  claim 1  wherein the at least one lubricating oil additive is selected from the group consisting of a salicylate, a carboxylate, a sulfonate, a phenate, a stearate, and an oxide. 
     
     
         11 . The method of  claim 1  wherein the at least one lubricating oil additive has a total sulfated ash from about 0.02 to about 0.17 wt %. 
     
     
         12 . The method of  claim 1  wherein the at least one lubricating oil additive 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 1  wherein the lubricating oil base stock comprises a Group II, Group III, or Group IV base oil. 
     
     
         14 . The method of  claim 1  wherein at least one lubricating oil additive concentration ranges from about 0.1 to about 20 weight percent, based on the total weight of the lubricating oil. 
     
     
         15 . The method of  claim 1  wherein the lubricating oil base stock concentration ranges from about 50 to about 99 weight percent, based on the total weight of the lubricating oil. 
     
     
         16 . The method of  claim 1  wherein the lubricating oil is a passenger vehicle engine oil (PVEO). 
     
     
         17 . A lubricating engine oil having a composition comprising a lubricating oil base stock as a major component; and at least one lubricating oil additive, as a minor component; wherein said lubricating engine oil contains at least one metal or metalloid in an amount sufficient that, in thermogravimetric measurements of the lubricating engine oil by a Thermogravimetric Engine Oil Simulation Test, carbon black decomposition temperature is increased as compared to the carbon black decomposition temperature in a lubricating engine oil containing calcium or magnesium. 
     
     
         18 . The lubricating engine oil of  claim 17  wherein, in thermogravimetric measurements of the lubricating engine oil by a Thermogravimetric Engine Oil Simulation Test, the carbon black decomposition temperature is increased by at least 10° C. as compared to the carbon black decomposition temperature in a lubricating engine oil containing calcium or magnesium. 
     
     
         19 . The lubricating engine oil of  claim 17  wherein, in thermogravimetric measurements of the lubricating engine oil by a Thermogravimetric Engine Oil Simulation Test, the carbon black decomposition temperature is increased by at least 25° C. as compared to the carbon black decomposition temperature in a lubricating engine oil containing calcium or magnesium. 
     
     
         20 . The lubricating engine oil of  claim 17  wherein the engine exhibits greater than about 10% reduced low speed pre-ignition, based on normalized low speed pre-ignition (LSPI) counts per 25,000 engine cycles, engine operation at 2000 revolutions per minute (RPM) and brake mean effective pressure (BMEP) at 18 bar, as compared to low speed pre-ignition performance achieved in an engine using a lubricating engine oil containing calcium or magnesium. 
     
     
         21 . The lubricating engine oil of  claim 17  wherein the at least one metal or metalloid comprises sodium, manganese, titanium, aluminum, or mixtures thereof. 
     
     
         22 . The lubricating engine oil of  claim 17  wherein the at least one metal or metalloid is present in the lubricating engine oil in an amount from about 100 ppm to about 25,000 ppm. 
     
     
         23 . The lubricating engine oil of  claim 17  wherein (i) the at least one metal or metalloid is present in the lubricating engine oil in an amount from about 100 ppm to about 1000 ppm; (ii) total base number (TBN), as measured by ASTM D2896, of the lubricating engine oil ranges from about 2 mg KOH to about 17 mg KOH; (iii) total sulfated ash of the lubricating engine oil ranges from about 0.01 to about 1 wt %. 
     
     
         24 . The lubricating engine oil of  claim 17  wherein the at least one metal or metalloid is incorporated into the lubricating engine oil by maintaining constant ash, maintaining constant detergent metal, maintaining constant total base number (TBN), or top treating. 
     
     
         25 . The lubricating engine oil of  claim 17  wherein the at least one metal or metalloid is incorporated into the lubricating oil through the at least one lubricating oil additive. 
     
     
         26 . The lubricating engine oil of  claim 17  wherein the at least one lubricating oil additive is selected from the group consisting of a salicylate, a carboxylate, a sulfonate, a phenate, a stearate, and an oxide. 
     
     
         27 . The lubricating engine oil of  claim 17  wherein the at least one lubricating oil additive has a total sulfated ash from about 0.02 to about 0.17 wt %. 
     
     
         28 . The lubricating engine oil of  claim 17  wherein the at least one lubricating oil additive 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. 
     
     
         29 . The lubricating engine oil of  claim 17  wherein the lubricating oil base stock comprises a Group II, Group III, or Group IV base oil. 
     
     
         30 . The lubricating engine oil of  claim 17  wherein at least one lubricating oil additive concentration ranges from about 0.1 to about 20 weight percent, based on the total weight of the lubricating engine oil. 
     
     
         31 . The lubricating engine oil of  claim 17  wherein the lubricating oil base stock concentration ranges from about 50 to about 99 weight percent, based on the total weight of the lubricating engine oil. 
     
     
         32 . The lubricating engine oil of  claim 17  which is a passenger vehicle engine oil (PVEO). 
     
     
         33 . An engine lubricated with the lubricating engine oil of  claim 17 .