Off Season Storage for Outboards
Revised by BoatUS editors in April 2012
Take extra care to make sure that your engine is properly protected, especially when storing. You'll need fuel conditioner, grease, gearbox lubricant, and storage fogging oil. This is only general guidance. Always follow the manufacturer’s instructions and recommendations and if these are inconsistent with anything here, defer to the manufacturer.
A good fuel conditioner that’s approved by the manufacturer may help to stabilize the fuel that you have in your engine's system to ensure that the fuel is free of water and other foreign bodies when you restart the engine in the spring. Also, fuel tends to break down during long periods of storage, transforming itself into a gummy substance that clogs your carburetor and fuel lines. Better to take care of it before the clogging happens than face stripping down your fuel system.
Fogging oil is used to prevent damaging corrosion from forming inside the engine during winter storage. The oil comes in an aerosol with a micro straw that can direct the spray into the carburetor throat and spark plug holes. Follow recommendations for your engine, including the product to use.
For extra protection, remove the spark plugs and spray fogging oil in the holes to assure the cylinders and rings are also well lubricated. Rotate the flywheel a few turns to spread the oil inside and then put the plugs back in.
You should also drain and refill your gearbox with fresh oil and lubricate all the lube points on your engine such as shift and throttle linkages. Leave your oil system connected, first making sure that your oil tank is full. This will reduce or prevent condensation forming in the tank during storage.
Remove and check your propeller for damage. If you're unsure of what to look for, don't hesitate to take it to a prop shop or your dealer. Clean and lubricate the shaft. Take the opportunity to tighten any loose screws, nuts, and bolts, and wax the engine's external surfaces. Check and clean your battery, storing it in a cool, dry place.
A final consideration is the position in which to store your engine. The best way is to either leave the motor on the boat or on an engine stand in an upright position, not tilted. If neither of these are an option, try to make sure that the engine is in an upright, self-draining position. If you can't do this, be sure that the cooling system is drained completely. Also, don't store the motor with the gearbox higher than the powerhead, since any water in the exhaust passages can run into the cylinders and cause serious damage. Look carefully at all the mounting hardware you loosen or remove from an installed engine. Replace if there is any wear or other impairment. Also, protect the motor from insects such as mud daubers that may stop up cooling and other holes.
If you follow these basic recommendations, your engine should give you years of trouble-free service. Take the time before storing your motor and you'll have an easy spring!