The present application concerns the use, for cooling and/or lubricating a propulsion system of an electric or hybrid vehicle, of an aqueous lubricating composition comprising at least: water and a polyalkylene glycol; the said aqueous lubricating composition comprising a phosphate ester salt(s) content of strictly less than 0.1% by mass, relative to the total mass of the said composition.

It also relates to the use of such an aqueous lubricant composition to reduce pitting by mechanical fatigue of the mechanical part(s) of an electric or hybrid vehicle propulsion system which is (are) brought into contact with the said composition.

Lastly, it relates to an aqueous lubricating composition for lubricating and/or cooling an electric or hybrid propulsion system, comprising: at least 45% by mass of water, relative to the total mass of the composition, and a polyalkylene glycol; the said composition comprising a phosphate ester salt(s) content of strictly less than 0.1% by mass, relative to the total mass of the said composition.

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.

There has been a demand for a lubricating oil composition that has excellent cooling performance and insulating properties. This lubricating oil composition contains a base oil (A), solid particles (B) that have an average primary particle diameter of 500 nm or less, and a dispersant (C); the content of the solid particles (B) is 0.1 to 30% by mass based on the total amount of the lubricating oil composition; and the content of the dispersant (C) is 0.1 to 20% by mass based on the total amount of the lubricating oil composition.

This invention relates to a lubricating oil composition for hybrid engines including a) an oil of lubricating viscosity at greater than 50 wt. % of the composition comprising a Group I, II, III or IV base oil, or combinations thereof; b) one or more, optionally borated, higher molecular weight polyisobutylene succinimide (PIBSA-PAM) dispersant (Mn 1600 g/mol or more); c) optionally one or more, optionally borated, lower molecular weight polyisobutylene succinimide (PIBSA-PAM) dispersant (Mn less than 1600 g/mol), wherein the treat level of the combination of the higher molecular weight PIBSA-PAM and lower molecular weight PIBSA-PAM is from 1.0 to 12.0 wt. % of the composition, and wherein the treat level of the higher molecular weight PIBSA-PAM is from 1.0 to 9.0 wt. % of the composition; and d) an overbased calcium salicylate or sulfonate detergent, an overbased magnesium salicylate or sulfonate detergent, an overbased mixed calcium and magnesium salicylate or sulfonate detergent or a combination thereof, wherein the detergent has a Total Base Number (KOH/g) greater than or equal to 9 and less than or equal to 500 and delivers at least 5 mmol of total soap to the composition. Also provided is a method of evaluating a lubricating oil composition for ranking its performance in a hybrid engine by running a bench scale test protocol based upon 3 test results: the emulsion dispersion and stability performance at all 4 test conditions in the Emulsion Stability test (modified ASTM D7563), the emulsion corrosion test, and the journal bearing wear test.