Lets say that you did everything you need to do in order to winterize your outboard for the winter months. You stabilized the gas, changed the gear lube, and fogged the cylinders. You did all of that. I mean what else do you need to do to make sure you don't have any problems when the cold weather hits? Well actually there are a few more things you should make sure you do to ensure you have a working outboard come spring time.
One of the first mistakes people make after winterizing their boat is that they leave the motor tilted in the upwards position. This is not going to allow the water to drain out of the motors cooling system. Instead you will want to trim or tilt the outboard all the way down so that the water drains out of the motor when you park it for the winter. This is especially important if you store your boat outside. If you have it tilted up, you can still have water in the motor which can freeze causing your block to crack or damage your water pump. Rain and snow can also enter through your prop hub, end up freezing with colder temps, and possibly causing damage.
Another mistake people make is covering the motor with plastic when they wrap it for storage. Yeah, you might think this is going to keep your motor clean and safe from the elements, but this is actually not allowing the motor to breath with the change in temps. Cowls are vented and designed to breath to keep moisture from collecting on the powerhead and causing corrosion problems. By covering the motor you are creating condensation which will lead to corrosion in the charging system and other various components.
The third mistake I see sometimes is people running their motor dry thinking that they are draining the rest of the water out from the cooling system. DON'T. This is bad news and should never be done what so ever. Outboard cooling systems self drain and outboard water pumps depend on water for lubrication. Running your motor dry will cause damage to the water pump impeller or possibly even ruin it. Just make sure that you always run your motor in the water, in a tank, or on the hose with earmuffs.
Lastly don't keep your batteries in your boat during the off season. This is something I see every year. Batteries won’t freeze if they have a good charge, but if the charge is low, it will freeze and be junk by spring. Yeah it's only 130 or so dollars and its not a major component of the outboard, but why would you want to have to pay that money on a new battery when you could buy more fishing gear or a new pole? Just make sure that you take them out, give them a full charge, store them some place cool and off of the cement.