Winterizing your plane

A couple of days ago when I went out for my morning walk I noticed something had changed. Instead of warm and sunny, there was a chill in the air. I then realized that fall is approaching and I needed a jacket.

The same kind of thing happens to many pilots each year. They are enjoying the nice flying weather when all of a sudden, winter is upon them, so they put their plane away and figure they will just change the oil in the spring before they do any more flying. There is a big problem with this plan.

When an engine is operated, a small amount of fuel and combustion by-products go past the rings and into the oil. Called blow-by, this contains many different compounds, including sulfur from the fuel. These contaminates can increase corrosion and rust, especially when moisture enters the engine from rising and falling temperatures during the long winter storage period.

If you do not plan on flying much — or at all — during the winter, make sure you change the oil before you put your plane away. I also recommend you add one quart of preservative oil as part of the oil change. It is also good to do a short flight on the oil, if possible, to ensure that all of the parts of the engine are supplied with new oil.

If you live in a warmer climate or use your plane all winter long, then you should stay with your normal, every four months oil change schedule. However, I recommend that you consider using a multigrade oil during the winter months, especially if you do not have any pre-heat equipment and/or plan on flying into colder climates. Multigrade oils do not eliminate the need for pre-heating; they just give you an extra margin of safety during cold start conditions.

On the fuel side, there is not much that needs to be done. If you use auto gas, remember that it is good for about six months. If you are going to let your plane sit longer than that, you probably should fill up with 100LL before you put it in storage.

A major concern about auto gas that contains ethanol is that during storage, it absorbs water and becomes quite corrosive. If there is a chance that you received some fuel with ethanol in your plane, I recommend draining the tank completely and refilling with a known good fuel.

There is no need to change grease, since all qualified aviation greases have excellent low temperature properties. However, there is one concern: Many pilots take great pride in their aircraft so they like to clean it well before putting it up for the winter. The concern I have here is power washing. The seals on bearings are designed to keep grease in. If a small amount of high pressure water hits the outside of the seal either directly or indirectly, it can easily force water into the bearing area. When your plane sits over the winter, the freeze and thaw cycle will be repeated many times and this can cause harm to the bearing and/or the seal. Do not get a power wash stream near any bearings on your aircraft. I know of several pilots who have said they redo the wheel bearings every fall to ensure against any moisture in the bearing area.

This is not a complete list of all of the steps needed to winterize your aircraft; it is just a few suggestions in the fuels and lubes area that can help ensure a longer, safer aircraft over the long haul.

Ben Visser is an aviation fuels and lubricants expert who spent 33 years with Shell Oil. He has been a private pilot since 1985. You can contact him at

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