Abstract: This disclosure relates to lubricating engines using formulated lubricating oils to reduce wear and improve engine fuel efficiency. The formulated lubricating oils contain a major amount of a nonpolar lubricating oil base stock and a minor amount of one or more polar lubricating oil additives. The one or more polar lubricating oil additives include swollen inverse micelles dispersed in the nonpolar lubricating oil base stock. The swollen inverse micelles include (i) a liquid polar core containing a polar solvent and one or more polar lubricating oil additives having solubility in the polar solvent, and (ii) a layer of liquid surfactant molecules enclosing the liquid polar core in which polar heads of the liquid surfactant molecules are oriented towards the liquid polar core. A method of improving solubility of polar lubricating oil additives in a nonpolar lubricating oil base stock is also provided.

Abstract: Provided is a method of improving nitrile seal compatibility with a lubricating oil in an engine lubricated with the lubricating oil. The method includes using as the lubricating oil a formulated oil comprising a lubricating oil base stock as a major component and an alkylated aromatic base stock as a minor component. Nitrile seal compatibility is improved as compared to nitrile seal compatibility achieved using a lubricating oil containing a minor component other than the alkylated aromatic base stock, e.g., an ester. A lubricating engine oil comprising a lubricating oil base stock as a major component and an alkylated aromatic base stock as a minor component. The alkylated aromatic base stock is present in an amount sufficient for the lubricating oil to exhibit improved nitrile seal compatibility as compared to nitrile seal compatibility achieved using a lubricating oil containing a minor component other than the alkylated aromatic base stock.

Abstract: Provided are a lubricating engine oil and a method of improving nitrile seal compatibility with a lubricating oil in an engine lubricated with such lubricating oil. The method includes using as the lubricating oil a formulated oil comprising a lubricating oil base stock as a major component and one or more additives selected from the group consisting of (i) a sulfone, sulfolane, or derivative thereof; (ii) a borate ester, boron amide, or mixtures thereof; (iii) a sulfurized olefin; (iv) a thiadiazole or derivative thereof; and (v) a succinic anhydride or derivative thereof, as a minor component. Nitrile seal compatibility is improved as compared to nitrile seal compatibility achieved using a lubricating oil containing a minor component other than the one or more additives.