Abstract: A novel oil changer designed to enable one to visually determine the extent of contamination or deterioration of oil in service in comparison with fresh oil prior to change thereof for the purpose of attaining highly economical oil consumption. The oil changer includes an oil contamination inspection tank adapted to be selectively placed into communication with an external oil sump and a waste oil reservoir for forced passage therebetween of used oil under the drive of a pneumatically driven pump, and a metering tank for storing and metering fresh oil to be delivered therefrom to said external oil sump and adapted to be selectively placed into communication with a fresh oil reservoir and said metering tank for forced passage therebetween of fresh oil under the drive of a reversible pneumatically driven pump.