Mike Busch Maintenance Forums

[Bill Greenwood]

I went to two maintenance forums by Mike Busch, and it seems worthwhile.

But I have some questions in one area; that of the forum on oil types.
Mike says the main item of wear in an aviation piston engine is from corrosion, as when the engine is not being flown and is sitting.
He than picks his favorite oil type on this basis.
Now the conditions where a plane is based are a factor, for instance in the humid salty climate of the Gulf coast it may be a big factor.

But Mike really did not mention friction wear, especially on first start up on an engine which has not run in awhile and which is devoid of oil in the upper end.
I think this is the source of much wear, not just corrosion, especially where I live in Colorado that is very dry and part of the year is cold.
He likes single weight oil, like Aeroshell w100, and didn't advocate preheating the oil, before start up. I think in many parts of the country that will lead to wear on initial running.

I use a multigrade and usually preheat, or try to. Even in May or Sept we may have night temps down around 40 degrees and 100 weight oil doesn't pump very well through small engine passages then.

He also advocates changing oil every 4 months on a time basis, not just hours run. I don't know anyone who does that, don't know if it is good or overkill.

He likes oil analysis and checking the filter. It has been my experience that if the filter is clean, the analysis is likely to be also.

This is all sort of informed guess work or personal experience. No one takes 100 of the same engines and runs half of them on multigrade and the other half on w100, in the same conditions, to see the actual results, like you'd need to to the really have factual reports.

[turtle]

But Mike really did not mention friction wear, especially on first start up on an engine which has not run in awhile and which is devoid of oil in the upper end.
I think this is the source of much wear, not just corrosion, especially where I live in Colorado that is very dry and part of the year is cold.

To prevent corrosion you want an oil that won't run off and leave the upper end dry. So solving one problem solves another. I agree with the need to preheat. I use W80 in the winter so preheating is not really optional. Even using multigrade, preheating is much easier on the engine. What you don't want to do is run a heater then not fly the plane.

[Bill Greenwood]

I am not very convinced about this idea of "an oil that won't run off" and leave the upper end dry.

Now,there are some tests or rather demonstrations that try to show that thick oil won't run off of a part like a thin oil will. But it is not very convincing. First ,when an engine shuts down after a flight, the internal parts are several hundred degrees. Any oil, be it 15-50 , or w100 is going to be thin at that temp and "run off". It's not cosmoline grease! And all parts are not vertical anyway.

What is needed is an oil that is thin enough when cold to flow on start up and provide good lubrication right away. And id the weather is cold or even cool enough to prevent that thick oil from flowing, then the small amount that is left on a part after shut down is unlikely to provide enough lubrication to prevent wear on starting up.

[WLIU]

Lyco engines splash lube their cams unlike auto engines. The cam is above the crankshaft. If the oil is thin enough to run off while the airplane sits, the cam gets a lot of wear on start up until enough oil is thrown up onto it. Cam bearing loads are not a function of RPM but more a function of the valve springs so starting slow does not reduce cam wear. See the issues with the O-320 -H engines in the Skyhawks.

It takes even longer for oil to get to the top end of the cylinders. Take your rocker covers off some time, wipe down the residual oil, start the engine and watch. You will be surprised.

Multigrade is great if you fly a lot. Not so much if you fly a couple of hours a month. Mike B is no dummy.

Best of luck,

Wes
N78PS

[Bill Greenwood]

Wes, you may have misunderstood what I thought I wrote. Nothing I wrote was that Mike is a dummy.
But I question some of his ideas from the forum on Fri.
1. That corrosion is the number one wear item.
He barely mentions friction wear, including start up wear from not having oil pumped through the engine instantly.
2. That thicker base stock oil is better, because it does not "run off" as easily after engine shut down and thus protects against corrosion.

And as for as seeing oil being pumped with the rocker covers off, while I have not seen it myself, I am told that in some cases like a Merlin it can take a minute to get oil up to the upper end cams and followers.

I think anything one can do to shorten this waiting time for upper end lube is good, and the two main things are most likely to be using multigrade oil which will flow on start up even if fairly cold, and to preheat if possible anytime it is cold .
There are people who claim they don't need to preheat because they live in the south, but I have seen it below freezing in both Texas and Florida.

I don't think the answer to wear, is to use thick stock oil which will not flow well when cold and hope that enough of the thick oil will stay on the parts when shut down to protect the parts on the dry start up.

I don't use a Lycoming now, but when I did have a IO-360 in my Mooney M20J it went to 2000 TBO using multigrade oil, Aeroshell 15-50.
I don't really see this question of what makes most of the wear as dependent on whether one has a Lycoming or Continental or other make.

[Joe Delene]

I was able to fit in one of his seminars dealing mostly with leaning. I enjoyed it, learned a few things too. I also read his stuff in Sport Aviation 1st thing. It is impossible for us to treat 2 engines the same & with different oil, them compare results. Most are lucky to have one engine.

In my 0320, S WI I use 100w + Shell in the summer & 15w-50 from mid fall to mid spring. I also preheat with night temps below 45 or so. I only preheat 24 hours or less before a flight if needed, not plugged in all the time in the winter. I also try to never go over 14 days or so without a flight. I've not yet felt the need to do the Camguard thing. I have given it some thought & I do think it could be an added benefit, it's the AMOUNT of benefit I debate. My main focus is an oil change around the 4-5 month window, the hours may be 25-35, depending.

If I anticipate the plane won't get flown a lot, I like clean oil in it. I would still take it up every 2 weeks or so for 30 minutes minimum.

My usual rotation is 3 oil changes a year, 2 myself & one with the annual. I bought a 6 pack of Tempest filters at Airventure so I'm good for a while. I just don't like dirty oil sitting in the engine. Maybe I could back that off to 2 changes, not quite there yet though. I do think Camguard is more helful if you plan to sit a while without flying.