Hi Jeremy, welcome to the club.



Almost as good as the Elks lodge!

When my plane sits, I don't turn it over. IMHO, you wipe the protective oil film from the walls and and pressure point of the engine from the squeeze of any rollers or lifters. When I want to do anything, I take and run up and fly to get to temperature and evaporate any moisture and contaminates from the crankcase. This is my thoughts as a truck mechanic trying to get the best life out of my C-145. I don't use heaters until I am ready to fly and then preheat.

John

Yeah, there are lots of theories about this topic, but some of them are wrong. And now, I will prove it.

Recently, we were doing the C of A on my friends RV-4 with an O-320. We wanted the engine's top end warmed up to do the leak-down check so we did a ground run-up until we got some decent cyl. head temps and shut it down. We pulled the plugs and went ahead with the leakdown testing. So far so good. One of the cylinders seemed a little soft so we removed the valve cover on that cylinder head to inspect the valves and listen to the leakdown airflow.

I was absolutely shocked when I pulled off that valve cover because it was RUNNING with water. I'll bet there was two tablespoons of water trapped in there. So, think about that when you do a 10 or 15 minute ground run to keep your engine "healthy". You just introduced a whole bunch of water into your cylinder heads that will sit until the next time, when you will add some more?!?!

To further drive home the futility of this "Unhealthy" practice, I must tell you about a freshly rebuilt Cessna 180 that I bought back in the 80's. The engine was "0" timed and the caretaker of the airplane told me that he ran the engine religiously every week. The airplane was stored outside in the Pacific NorthWest, over the winter months when I first looked at it. The caretaker, had been running the engine once a week for about six months when I happened on the aircraft.

I bought the airplane, and loved it immensely. I lavished it with care and poured even more money into it by fitting it with a Robertson STOL kit, and then had it certified for IFR flight. Very expensive projects!

Things went well, until one day I noticed that the power was low during a STOL takeoff out of a 500 foot strip. I had my mechanic check the engine and one cylinder had NO COMPRESSION?? We removed the jug and found that the top of the head was cracked about 300 degrees out of 360.

The crunch came though when looking inside the crankcase with the cylinder removed. The inside of the engine was a seething mass of rust! The crankshaft had to be replaced and basically the engine had to be majored. This cost me so much money that I had to sell the aircraft to survive. (I had 3 small children at home and I was a single Dad) Anyway, the story is told so that you realize the danger of ground running an engine during winter to supposedly keep it healthy. And this is especially true for a freshly majored engine with new, shiny, unglazed internals. After a few hundred hours, the oil will bake onto most of the parts and preclude some of the rusting.

A better thing to do is to get 4, or 6 of those spark plug dessicant containers and put them into the top plug holes. Right after squirting some oil into the cylinder and turning the engine over a bit. The dessicant will keep the moisture out of the cylinders and the color of the dessicant will change if the material becomes saturated. You can then bake the dessicant and reuse it.

I personally don't think it would hurt to turn the engine over a couple of revolutions per month, just so the same valve springs will not stay in compression for the entire winter. The dessicant will handle any moisture dragged into the cylinder during this procedure.

Cheers, Pete