I’ve always been told ground runs are meaningless. You need to fly it and put load on it to get moisture out of oil. But then again, isn’t it better that cams etc get coated with oil rather than not? Corrosion happens quicker on uncoated items, even though there is moisture in oil as well. I would run it.
I don’t understand the engineering justification for ground runs being meaningless.
Running the engine will lubricate it no matter where it is running. And to boil off the water from the oil, it needs to be at cruise temperature for long enough… I set myself 45 mins as the shortest flight. I am sure say 15 mins is not enough. The truth will probably be somewhere in between, and the overall corrosion susceptibility picture will depend on where the plane is stored, is Camguard used, history under previous owners (declared or undeclared long inactive periods), etc.
Most private aircrafts sits for longer periods than that. I am not saying it is good but if you let it do that once it should not be a problem.
AdamFrisch wrote:
Corrosion happens quicker on uncoated items, even though there is moisture in oil as well. I would run it.
The exposed parts are made of high quality steel. That’s not the same as iron nails that corrode in a week. Also pilots forget where the moisture in the crankcase is coming from: from running the engine! If you fly the airplane for 1h after having it sit for a month, there will be more water in the crankcase than before! Only that the oil is hopefully hot enough and cools slowly enough for most of the water to evaporate.
Try opening your oil filler neck right after landing and see how much vapor comes out. So flying the airplane = add water to the oil. Stopping the engine with hot oil = lose water.
I read (Mike Bush?) that one hour of flight time once a month as a minimum is sufficient. That`s what I`m doing.
You have to let the water escape, e.g. by opening the oil inlet, there you can see the water coming out as smoke. I do that after every flight, winter and summer.
And I use CAMGUARD, but I have not yet seen proof of its effectiveness.
highflyer wrote:
there you can see the water coming out as smoke
“Smoke” is a visible suspension of particles in air, usually from burning a substance.
“Vapor” is a diffused/suspended liquid in air.
I hope you’re seeing vapor, not smoke 
An exposed camshaft surface will rust within days if exposed to moist air and not protected by an oil layer. The Q is whether this is the case in the engine. Machine tools (high grade hard steel, often case hardened like the camshaft parts) rust within days in the right conditions (I happen to know this).
I posted the Camguard data in the Camguard thread. Oil analysis clearly shows a big reduction in the wear of the hard metals. And I fly once a week.
The oil temp reaches something like +70C which is not enough to boil water off immediately (you would need +100C for that, at sea level pressure) but during flight the pressure is lower, but against that you have the pressurisation in the crankcase (I posted a crankcase pressure test here some time ago, in the piston ring thread) so maybe there is no net effect there. But on a ground run you will have no altitude benefit but you will have the crankcase pressurisation.
Once a month is probably OK if you use Camguard and the plane is hangared, hopefully not close to the sea.
Unfortunately the data points on this whole thing are too random, largely due to
We have had loads of threads on this topic but every case I have seen of a Lyco engine which “disintegrated” due to camshaft / follower corrosion had an unverifiable history (1 or more points above especially #1).
Peter wrote:
We have had loads of threads on this topic but every case I have seen of a Lyco engine which “disintegrated” due to camshaft / follower corrosion had an unverifiable history (1 or more points above especially #1).
I’ve also seen one “disintegrate” after a fully verifiable history – flying club plane, typical usage 40-80 hours per month, flew every day (reached TBO on average once every 2 years). Cam failed on one engine halfway to TBO due to corrosion and spalling.
Someone did some tests:
oil protection
achimha wrote:
I hope you’re seeing vapor, not smoke
OK 1:0
