Lubricant composition for preventing pre-ignition

Abstract

The present invention relates to the use of a lubricant composition comprising (i) at least one dithiocarbamate compound; and (ii) at least one base oil, for preventing and/or reducing pre-ignition, in particular at low speed, in a vehicle engine, wherein said composition is applied during at least one change interval without the addition of a new lubricant composition, the content of dithiocarbamate compound being less than or equal to 1% by weight relative to the total weight of the lubricant composition.

1 - 15 . (canceled) 
     
     
         16 . A method for preventing and/or reducing preignition in a vehicle engine, the method comprising contacting the engine with a lubricant composition in the course of at least one oil change interval without adding fresh lubricant composition, the lubricant composition comprising:
 (i) at least one dithiocarbamate compound; and   (ii) at least one base oil;   wherein the lubricant composition comprises dithiocarbamate compounds in an amount less than or equal to 1% by weight, relative to the total weight of the lubricant composition.   
     
     
         17 . The method of  claim 16 , wherein the dithiocarbamate compound is chosen from metal dithiocarbamates, bisdithiocarbamates, or mixtures thereof. 
     
     
         18 . The method of  claim 16 , wherein the lubricant composition comprises dithiocarbamate compounds in an amount ranging from 0.02% to 1% by weight, relative to the total weight of the composition. 
     
     
         19 . The method of  claim 16 , wherein the base oil is chosen from the oils of group III, the oils of group IV, or mixtures thereof. 
     
     
         20 . The method of  claim 16 , wherein the lubricant composition further comprises at least one antioxidant additive different from the at least one dithiocarbamate compound. 
     
     
         21 . The method of  claim 20 , wherein the at least one antioxidant additive is present in an amount ranging from 0.05% to 2% by weight, relative to the total weight of the lubricant composition. 
     
     
         22 . The method of  claim 16 , wherein the lubricant composition further comprises at least one detergent additive chosen from alkaline-earth metal salts. 
     
     
         23 . The method of  claim 16 , wherein the lubricant composition comprises at least one viscosity index-enhancing additive chosen from hydrogenated or non-hydrogenated homopolymers or copolymers, styrene, butadiene, or isoprene. 
     
     
         24 . The method of  claim 23 , wherein the composition comprises from 2% to 15% by weight of viscosity index-enhancing additive, relative to the total weight of the composition. 
     
     
         25 . A method for preventing and/or reducing preignition in a vehicle engine, the method comprising adding at least one dithiocarbamate compound to a lubricant composition comprising at least one base oil, wherein the lubricant composition is used in the course of at least one oil change interval without adding fresh lubricant composition. 
     
     
         26 . A method for limiting the degradation of performance in terms of preventing and/or reducing preignition in a vehicle engine of a lubricant composition comprising at least one base oil, after its use in the course of at least one oil change interval without adding fresh lubricant composition, the method comprising adding at least one dithiocarbamate compound to a lubricant composition. 
     
     
         27 . A method for increasing the ignition temperature, measured by high-pressure differential scanning calorimetry, of a lubricant composition comprising adding at least one dithiocarbamate compound to said lubricant composition, said composition being used in the course of at least one oil change interval without adding fresh lubricant composition, relative to a spent lubricant composition free of any dithiocarbamate compound. 
     
     
         28 . A process for preventing and/or reducing preignition in a vehicle engine, comprising:
 a) contacting the engine with a lubricant composition comprising at least one base oil and at least one dithiocarbamate compound, wherein the lubricant composition comprises dithiocarbamate compounds in an amount less than or equal to 1% by weight, relative to the total weight of the lubricant composition; and   b) running the engine in the course of at least one oil change interval, without adding fresh lubricant composition.   
     
     
         29 . The process as claimed in  claim 28 , wherein the dithiocarbamate compound is chosen from metal dithiocarbamates, bisdithiocarbamates, or mixtures thereof. 
     
     
         30 . A method for preventing and/or reducing preignition in a vehicle engine, comprising at least a step of contacting the engine with a lubricant composition comprising:
 (i) at least one dithiocarbamate compound; and   (ii) at least one base oil;   wherein the lubricant composition has undergone iron-catalyzed oxidation at a temperature ranging from 150° C. to 170° C. for a time ranging from 120 hours to 150 hours, according to the GFC Lu-43A-11 method.   
     
     
         31 . The method of  claim 16 , wherein the lubricant composition is contacted with the engine over a distance travelled by the vehicle ranging from 10,000 km to 30,000 km, without adding fresh lubricant composition. 
     
     
         32 . The method of  claim 16 , wherein the dithiocarbamate compound is chosen from molybdenum dithiocarbamate, methylene bis(dibutyldithiocarbamate), or mixtures thereof. 
     
     
         33 . The method of  claim 16 , wherein the content of dithiocarbamate compound ranges from 0.1% to 0.5% by weight, relative to the total weight of the composition. 
     
     
         34 . The method of  claim 20 , wherein the antioxidant additive is chosen from diphenylamine, phenols, phenol esters, or mixtures thereof. 
     
     
         35 . A method for preventing and/or reducing low-speed preignition in a vehicle engine of a motor vehicle, the method comprising contacting the engine with a lubricant composition in the course of at least one oil change interval without adding fresh lubricant composition, the lubricant composition comprising:
 (i) at least one dithiocarbamate compound; and   (ii) at least one base oil;   wherein the lubricant composition comprises dithiocarbamate compounds in an amount less than or equal to 1% by weight, relative to the total weight of the lubricant composition.