A method of recovering heavy oil from a subterranean reservoir. The method includes injecting steam into a subterranean reservoir to heat heavy oil in the subterranean reservoir and thereby produce heavy oil of reduced viscosity; injecting a multi-purpose agent into the subterranean reservoir; and producing the heavy oil of reduced viscosity from the subterranean reservoir after injecting the steam and the multi-purpose agent. The multi-purpose agent comprises an ester of the formula RxCOORy wherein Rx is a straight chained or branched alkyl group having 1 to 8 carbon atoms, Ry is a straight chained or branched alkyl group having 1 to 12 carbon atoms, C is carbon and O is oxygen.