Last week we had a hard freeze here in the upper midwest. This brought some good news and some bad news. On the down side, it meant the end of fresh BLTs with tomatoes that actually had some taste. Also, I am about out of fresh apples. But on the positive side, I have not seen a mosquito all week and the flies are all about dead. Another plus is the beautiful colors of the leaves on the trees and bushes, plus the crisp clean air every morning.
Why am I talking about signs of colder weather in an aviation fuels and lubricants column? What does fall have to do with your average general aviation aircraft? It is one of the most important times because for almost every plane it is time to change the oil.
If you plan to use your aircraft all winter, now would be a great time to change to a multigrade oil if you don’t already use it. Even if you live in a warmer climate, a multigrade oil gives you better oil flow to all parts of your engine after engine start, especially in cool weather. It also gives you the capability to fly north during the winter and have an oil that will perform well wherever you would go.
But what about aircraft that are going to be put in storage or flown very little during the colder months?
Some aircraft owners will just put their plane in a hangar or tie it down without changing the oil and filter. Then in the spring, they change the oil so that they are starting off with fresh oil.
But there’s a problem with that: The aircraft will be sitting all winter with that used oil, which contains contaminates and acid buildup from the summer’s operation. The used oil will not offer good anti-rust protection through the temperature cycles that occur during the winter months.
This is important for all aircraft, but especially on Lycoming engines where the camshaft is above the crankshaft.
If you change the oil before putting your aircraft away for the winter, it will have fresh oil to provide anti-rust and corrosion protection.
I also recommend you add a quart or two of the corrosion protection oil Aeroshell Oil 2F or the Phillips Anti-Rust Oil. These products are flyaway oils qualified against Mil-C-6529C type II specification. This specification was developed during World War II to protect spare engines as they were transported across oceans and has worked well ever since.
The Process
When you change the oil, you should fly your aircraft until the oil temperature reaches around 180°F. After you land, drain the oil while it is still hot. This will ensure that almost all of the contaminates are drained out.
Now add the new oil and 2F and run the engine up to coat all the parts, especially the cam and lifter.
There may be additional steps you may wish to take before putting your airplane away.
During the winter months DO NOT go out to the airport and start the engine up to recoat the critical wear parts. Instead of helping, you will be pumping raw fuel into the engine and mixing it with water that has condensed during storage to form acids, which will increase corrosion.
If you want to go flying on a nice day, that is OK as long as you fly long enough to get the oil temperature up to 180°F to boil off the moisture that has accumulated.
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