Winterizing Your Lawnmower

As winter approaches, it reminds us that it is time to winterize not only your home and car, but also your gasoline-powered equipment such as lawn mowers and chain saws. Winterizing will help extend the life of your small gasoline engines.

To winterize your small gasoline engines there are two different approaches you can take:

Check the owner's manual for information on draining the fuel system for off-season storage. If recommended for your specific model, draining the tank will reduce evaporative emissions that occur during storage, according to the Engine Manufacturers Association (EMA). EMA is a Chicago based trade association for manufacturers of engines used in many applications including ground care equipment.
If the owner's manual says the gasoline can removed and it can be done easily, the gasoline should be carefully drained from the tank (and carburetor, if possible) and collected in a clean, approved storage container. Any remaining gasoline in the system can be removed by operating the engine until it stops. If you want to make the extra effort, adding a small amount of oil through the spark plug port also helps winterize an engine.
The collected gasoline can be used in your car.

If the gasoline cannot be easily removed, a gasoline stabilizer should be added to the fuel in the tank. To minimize air space in the engine's fuel tank, fill the tank full with the gasoline/stabilizer mixture. The engine should be operated for a few minutes to draw the stabilized gasoline into the carburetor. For added protection you may want to consider taking the time to close the engine's valves. For engines with hand-pull starters this can be done by pulling the cord until resistance is felt. Also an effective vapor barrier can be added by placing a piece of aluminum foil over the tank cap and then securing the foil with tape.
Whichever approach is taken, you should also store your motorized equipment in a cool, dry place that is well ventilated and out of direct sunlight.
Either winterizing approach is the same, regardless of whether you are using reformulated gasoline or conventional gasoline. Reformulated gasoline meets all the same requirements for storability as conventional gasoline. Therefore, reformulated gasoline is just as storable as conventional gasoline.

Winterizing is important because gasoline left in an engine's fuel tank and carburetor can degrade over time. During storage, gasoline can interact with air and moisture to form gums and deposits. Therefore you should not store gasoline in the engine's fuel tank for any inactive periods longer than one to two months.