Most cars take 4 to 5 quarts of motor oil, but one of the best ways to determine a car's oil capacity is to look in the owner's manual. If a manual isn't available, automobile manufacturer's websites or a website that offers information on oil capacity probably has the information.
Fluidcapacity.com links to the AMSOIL website, which provides oil grade and capacity in quarts or liters for major makes and models of cars. Using the AMSOIL search engine for a 2003 Toyota Camry four-cylinder reveals it takes 4 quarts of 5W-30 motor oil, for example.
Automobile dealer service departments, service stations or auto-parts stores may also provide a car's oil capacity with a phone call.