The LiquiVac Oil Changing System works by creating a vacuum that draws the oil out of an engine and into a plastic holding tank for disposal. To extract, one inserts the hose through the engine's dipstick tube, pumps the handle to create the vacuum power, then releases the valve. The product is available in two sizes-the 3-quart model for push and riding mowers, garden tractors, tillers, generators, snow throwers, and ATVs/UTVs; the 8-quart model for trucks, cars, tractors, combines, and other larger self-propelled machines. It's also handy for changing transmission oil and hydraulic fluid.