For most homeowners who need a generator for emergency or backup use, gasoline is the fuel of choice. Gas generators tend to have a lower price than other generator models, and except in extreme emergency situations, gasoline is readily available. Gasoline can have a relatively low shelf life though, and most blends begin breaking down or absorbing moisture within a month. Even gasoline that is several years old is viable, but it may contain elements that will break down or wear engine parts. Make sure you keep your gas generator clean of old fuel, and care for it like you would other gas powered small engines. If you plan to use your gas generator very infrequently, consider adding a fuel stabilizer or choosing a different type of fuel.