Abstract: An internal combustion engine oil change system including an oil filter equipped with a check valve fill fitting. During an oil change, new oil is supplied to the engine through the check valve fitting, thus both filling the filter with oil and back flushing the engine's oil pump. An oil supply mechanism including a tank adapted to hold an appropriate pre-measured quantity of oil under air pressure is provided. A flexible hose with a quick disconnect female coupling connects the tank to the filter fitting for delivering oil from the tank through the filter into the engine.