Lubricant composition having improved emulsion stability

Abstract

Disclosed is a lubricant composition comprising:at least one base oil,from 0.1% to 13% by mass of at least one viscosity index improver,at least one organomolybdenum compound, with the content of molybdenum element being at least 400 ppm by mass,at least a first detergent additive chosen from magnesium salts of carboxylic acids, of sulfonates, of salicylates, of naphthenates, of phenates and any mixture thereof,optionally, at least a second detergent additive chosen from calcium salts of carboxylic acids, of sulfonates, of salicylates, of naphthenates, of phenates and any mixture thereof,wherein the combined content of magnesium element and of calcium element, relative to the total mass of the lubricant composition, is at least 1000 ppm by mass.

1 . A lubricant composition comprising:
 at least one base oil,   from 0.1% to 13% by mass, relative to the total mass of the lubricant composition, of at least one viscosity index improver additive,   at least one organomolybdenum compound, with the content of molybdenum element being at least 400 ppm by mass, relative to the total mass of the lubricant composition,   at least a first detergent additive chosen from magnesium salts of carboxylic acids, of sulfonates, of salicylates, of naphthenates, of phenates and any mixture thereof,   optionally, at least a second detergent additive chosen from calcium salts of carboxylic acids, of sulfonates, of salicylates, of naphthenates, of phenates and any mixture thereof,   wherein the combined content of magnesium element and of calcium element, relative to the total mass of the lubricant composition, is at least 1000 ppm by mass.   
     
     
         2 . A lubricant composition according to  claim 1 , wherein the content of molybdenum element is less than or equal to 1,500 ppm by mass, relative to the total mass of the lubricant composition. 
     
     
         3 . A lubricant composition according to  claim 1 , wherein the first detergent additive is selected from among magnesium sulfonates. 
     
     
         4 . A lubricant composition according to  claim 1 , comprising at least a second detergent additive selected from among calcium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates and any mixture thereof; and wherein the ratio of the calcium element content to the magnesium element content ranges from 10:1 to 1:10. 
     
     
         5 . A lubricant composition according to  claim 4 , wherein the ratio of the calcium element content to the magnesium element content ranges from 5:1 to 1:5. 
     
     
         6 . A lubricant composition according to  claim 1 , wherein the second detergent additive is selected from among calcium carboxylates, preferably from calcium salicylates. 
     
     
         7 . A lubricant composition according to  claim 1 , wherein the organomolybdenum compound is selected from molybdenum dithiocarbamates. 
     
     
         8 . A method for the lubrication of a combustion engine, said method comprising bringing at least one part of the engine into contact with the lubricant composition of  claim 1 . 
     
     
         9 . The method according to  claim 8  for the lubrication of a combustion engine of a plug-in hybrid vehicle or of a hybrid vehicle with a range extender. 
     
     
         10 . The method according to  claim 8  in order to:
 prevent, and/or inhibit, and/or slow down problems associated with cold-starts of the said engine; and/or 
 prevent, and/or inhibit, and/or slow down corrosion phenomena that are likely to occur in the said engine; and/or 
 prevent, and/or inhibit, and/or slow down wear and tear of the said engine; and/or 
 prevent, and/or inhibit, and/or slow down the phenomena of demixing of the lubricant composition.