TRANSMISSION FLUID WITH SUPERIOR FRICTION PERFORMANCE

The friction performance of a lubricating oil composition which has been compounded to serve as a functional fluid and is particularly useful in mechanical and hydraulic units containing wet clutches, e.g. in automotive automatic transmissions, is greatly improved by the incorporation of a combustion of (a) afriction modifier of the type comprising a straight-chain alkenyl or alkyl C4 toC10 dicarboxylic acid or the reaction product of an aldehyde/tris-hydroxymethyl-aminomethane adduct and a long-chain dicarboxylic acid anhydride, such as an polyalkenyl succinic anhydride; with (b) an overbased detergent salts such as an alkali metal salt or alkaline earth metal salt of a hydrocarbyl sulfonic acid, an alkylphenol or a sulfurized alkyl phenol, in certain proportions.