Over the Thanksgiving weekend, I headed south to look at a classic car. As I was driving, I noticed a lot of pickups pulling campers heading south. Since several of the campers had stickers from the Aircraft Owners and Pilots Association (AOPA) and the Experimental Aircraft Association (EAA) on them, it led me to wonder what the pilots had done to preserve their aircraft before leaving?
The airframe and engine manufacturers have a list of items to do before parking an aircraft, so each pilot should check them out. I would like to address just the fuels and lubricant issues.
The number one thing to do to your aircraft is to change the engine oil BEFORE you put your plane up for the winter.
Many people think you need to change the oil in the spring so that you have fresh oil in the crankcase when you take the plane out to go flying. But this means that you leave the dirty contaminated oil in all winter, which promotes rust and corrosion.
Used oil contains dirt, but also unburned fuel and moisture. The small amount of sulfur and water will combine to form an acid, which will attack critical engine parts. So always change the oil before you park it.
It is not important what brand or grade of approved oil you use, if you do not intend to fly until warm weather. If you think you may fly some in the winter, then I would suggest you try a multi-grade oil. You can switch back and forth from single grade to multi-grade and it will not hurt your engine. You may notice a difference in oil consumption, but it should not hurt your engine in any way.
I would also strongly recommend that when changing the oil, you add one quart of an approved preservative oil to the oil charge. Both Phillips and Shell sell such a product that contains a Mil-L-6529C additive. These oils are approved for all certified aircraft engines.
And since you only have one quart in the engine, in the spring you can just go flying and you do not have to change the oil until your next scheduled oil change. The one quart level is recommended for most opposed engines. If you have a large radial engine, you may wish to increase the treat level proportionately. If your local lubricants supplier does not carry this product, you should check the oil company’s website.
If you fly only on 100LL, there is nothing you need to do before normal winter storage. If you fly on auto gas, you may wish to drain one tank and the carb. Then put in some 100LL and run it for a short time.
In the past, I have always said that auto gas was good for up to six months in storage. However, three years ago, I put fresh auto gas with some stabilizer in my four-stroke dirt bike before I put it in storage. In the spring, I had a lot of problems getting the bike going. The following fall, I again bought fresh auto gas, tested it for ethanol, added a stabilizer and put the bike up for the winter.
The next spring, the bike would not start and I had to rebuild the carb to get it to run. I talked this over with two bike shops and they both had the same problem. I told them I was going to try some 100LL in the tank before storage to see if that would fix the problem. This spring, the bike fired on the second kick, and the guys at the bike shops said that it cured all of their storage problems also.
Some people will also grease some of the bearings to force out any moisture. If you store your aircraft outside, it may be a good idea to plug exhaust and intake systems to keep snow, rain and dust from entering the cylinders that are sitting with the valves open.
When you do that I recommend that you make a list of all the actions taken and tape it to the dash. This will remind you to undo all of them before you go flying in the spring.
Remember that the mind is the second thing to go as we get older. I do not remember the first.