Lubricating oil compositions
AssigneeInfineum International Limited
InventorRobert Robson
Life of this patent
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Abstract
A low-phosphorus lubricant comprises: an oil of lubricating viscosity; a nitrogen-containing and a nitrogen-free dispersant; a metal dihydrocarbyl dithiophosphate; and a hydrocarbyl-substituted carboxylic acid derivative, the ratio of the dispersants being such as to provide suitable fluoroelastomer seal compatibility.
Claims15
A lubricating oil composition comprising
- (A) an oil of lubricating viscosity, in a major amount;
- (B) a nitrogen-containing lubricating oil dispersant, in a minor amount;
- (C) a nitrogen-free lubricating oil dispersant, in a minor amount;
- (D) a metal dihydrocarbyl dithiophosphate, in a minor amount;
- (E) a hydrocarbyl-substituted carboxylic acid or derivative thereof, in a minor amount;
- and
- (F) a metal detergent, in a minor amount,
- wherein the mass:mass ratio of (B) to (C) in the composition is 0.4:1 or greater, and the composition contains 0.075 or less mass % of phosphorus, expressed as elemental phosphorus.
A method of improving the fluoroelastomer compatibility of a lubricating oil composition containing a minor amount of dispersant and 0.075 mass % or less of phosphorus, expressed as elemental phosphorus, which method comprises selecting as said dispersant, a combination of (B) a nitrogen-containing lubricating oil dispersant and (C) a nitrogen-free lubricating oil dispersant, in a mass:mass ratio of (B) and (C) of at least 0.4:1, and providing a minor amount of (E) a hydrocarbyl-substituted carboxylic acid, or a derivative thereof.
Dependencies are inferred from the claim text.