For most boats go into storage during winter months. Gasoline lose octane and go bad. To protect my fuel I turn to AMSOIL and their gasoline stabilizer.
Amsoil Gasoline Sabilizer
Helps keep fuel fresh for up to 12 months. Fights oxidation to prevent the formation of varnish and sludge and keep floats and injectors clean for optimal engine performance. Ideal for stored seasonal equipment such as snowmobiles, lawnmowers, motorcycles and boats. Eases starting process when equipment is taken out of storage.
For maximum convenience and cost-effectiveness, equipment and vehicles used seasonally, such as motorcycles, snowmobiles, personal watercraft, snowblowers, outboard motors and classic cars, need to start easily and run properly when removed from storage. Gasoline, however, is not formulated for long-term storage and can start to degrade in as little as 30 days. Degraded fuel leads to varnish and sludge that clog injectors, fuel lines and carburetors; stick floats; and cause poor engine performance, starting problems, increased maintenance expenses and decreased equipment life.