Stored fuel can degrade due to chemical reactions, explains Family Handyman. You might be faced with ignition problems after only three months. Degraded fuel can also harm the motor.

Fuel stabilizer helps keep the fuel fresh, says Motor Biscuit, by stopping gas and ethanol from separating and causing damage. Before use, Consumer Reports advises that you consult the fuel stabilizer bottle itself for directions. Measure it according to the directions as you pour it into the gas tank. Then, start the engine so the stabilizer can flow into every nook and cranny of the fuel system.