A generator can take around 0.2 - 2.5 quarts of oil. The amount of oil for the generator depends on the size and oil capacity. A portable generator takes around 0.2 - 1.6 quarts and a house or office generator takes around 1.7 - 2.5 quarts of oil. Likewise, big generators take around 2.2 quarts. You may need a generator for various reasons.