If you check out Auto Zone, they usually have an "oil change special" where they sell you 5 quarts and a filter for anywhere from $8.99 - $14.99. The reasoning behind the 5 quarts is because the majority of all gasoline powered vehicles on the road today take 4 1/2 quarts from the factory. If you have a larger oil pan or a different dry/wet sump system, then it's different. Big blocks are also different. Diesels are different. But 90% of the gas powered 4, 6, and 8 cylinder gasoline engines take 4 1/2 quarts.