Oil capacity varies from one car to another. The best places to find the specific oil capacity include the owner's manual, manufacturer websites or specialty websites. As of 2014, Amsoil provides a guide that covers vehicles from 1980 to the present.
The dipstick, which may be located using the owner's manual, is also used to determine oil capacity. After the car has cooled for at least five minutes, pull out the dipstick and wipe it clean with a rag. Reinsert it, and pull it back out. Oil clings to the dipstick, and markings on the stick show the level the oil reaches. Fill the oil to the capacity line and determine how many quarts it took to determine total engine capacity.