Ashless engine lubricants for high temperature applications

An ashless lubricating oil having a composition comprising a lubricating oil base stock as a major component;

• and a mixture of (i) at least one ashless antiwear additive, (ii) at least one ashless detergent, and (iii) at least one aminic antioxidant, as minor components;
• wherein the lubricating oil base stock comprises at least one branched polyol ester, which is obtained by reacting one or more polyhydric alcohols with one or more branched mono-carboxylic acids containing at least 4 carbon atoms;
• and wherein the lubricating oil base stock is present in an amount from 30 to 99.8 mass percent, based on the total mass of the ashless lubricating oil.

A method for improving high temperature stability of a lubricating oil in an engine or other mechanical component lubricated with the lubricating oil by using as the lubricating oil an ashless formulated oil, said ashless formulated oil having a composition comprising a lubricating oil base stock as a major component;

• and a mixture of (i) at least one ashless antiwear additive, (ii) at least one ashless detergent, and (iii) at least one aminic antioxidant, as minor components;
• wherein the lubricating oil base stock comprises at least one branched polyol ester, which is obtained by reacting one or more polyhydric alcohols with one or more branched mono-carboxylic acids containing at least 4 carbon atoms, and at least one alkylated naphthalene;
• and wherein the lubricating oil base stock is present in an amount from 30 to 99.8 mass percent, based on the total mass of the lubricating oil.