MMO to break up the sludge

mondtster said:
Part of it depends on the oil you're using too. I bet you're using Phillips, right?

Regarding the oil consumption, you have to compare it to other similar engines. All the big continentals I've worked on and flown, regardless of cylinder finish are good on oil consumption when they have the 4 ring pistons. They didn't call the old 3 ring piston engines "OPEC engines" for nothing.

You can call it what you want, but it isn't an old wives tale. There are notable differences between engines of the same type running chrome cylinders and ones that aren't.
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Nope. Aeroshell. For the last decade or more. Since at least one owner ago.

I can call it whatever I like. There's little documented evidence of even 1/2 of the chromed cylinders doing this and even less documentation on how people operate their engines to cause it. Nor even the environments they're operated in.

Let me know when you find some hard evidence of it. Or at least someone's fleet test of at least 100 engines. The data to make a scientific analysis simply doesn't exist in any form that's reproducible or even organized.

The valves will have problems or the low end will make metal long before cylinders are a problem on an O-470 anyway. And there's a LOT of corroborated data that cylinders go when the metallurgy is wrong from ONE manufacturer. Which seems to be rampant in the newer stuff. That is 100% traceable and we have seen that numerous times in the last few decades. Problem is, good metallurgy at a name brand today doesn't mean they won't screw it up tomorrow.

But like you said, doesn't matter anyway. Popping a jug is what they were designed to have done. It's not particularly difficult.
 
denverpilot said:
I can call it whatever I like. There's little documented evidence of even 1/2 of the chromed cylinders doing this and even less documentation on how people operate their engines to cause it. Nor even the environments they're operated in.

Let me know when you find some hard evidence of it. Or at least someone's fleet test of at least 100 engines. The data to make a scientific analysis simply doesn't exist in any form that's reproducible or even organized.
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Considering that OEMs spend hundreds of thousands or maybe even millions on developing piston ring/cylinder finish combinations to minimize oil consumption and blowby, that is enough evidence for me. Further, I'm not aware of any Continental or Lycoming piston engine that comes from the factory with chromed cylinders so that should be an indication of something...

The chrome cylinder process was used in order to restore out of spec cylinders to within service limits. This was done in an era where new cylinders were expensive or nonexistent. When that is/was all that was available at the time I doubt people cared much about a little extra oil consumption or black oil.
 
I would never do this, but i've got this friend Ernie. Ernie puts in a quart of super high detergent motor oil an hour or so before the oil change, runs the schitte out of the engine for an hour and either drains it then, or hots it up again in a couple of days and does the Aeroshell oil change. Rinse, lather, repeat. Ernie has 2000 hours on the bottom end and a thousand hours on the jugs and a cleaner, tighter engine you've never seen.

Ernie worked for the airlines back in the dc7 days and relates how there was always a 55 gallon drum of mmo in the corner of the hangar under a pile of stuff so that the feds wouldn't see it on the odd hangar visit. Airplane comes in with a smoking, snorting engine, pour 5 gallons of mmo into it,take it over to a far corner of the airport, run the aforemention pshitte out of it for an hour and it comes back in the hangar purring like a kitten.

Ernie is a VERY good friend of mine and I know he wouldn't bs me.

Jim
 
mondtster said:
Considering that OEMs spend hundreds of thousands or maybe even millions on developing piston ring/cylinder finish combinations to minimize oil consumption and blowby, that is enough evidence for me. Further, I'm not aware of any Continental or Lycoming piston engine that comes from the factory with chromed cylinders so that should be an indication of something...

The chrome cylinder process was used in order to restore out of spec cylinders to within service limits. This was done in an era where new cylinders were expensive or nonexistent. When that is/was all that was available at the time I doubt people cared much about a little extra oil consumption or black oil.
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This being the same manufacturers who have both had to recall their jugs? :)

And yeah, you're right. The time where "people didn't care much" is still here.

Never seen a rental that didn't burn oil and never seen one with clean oil either. But my non-rental doesn't. Most of those have non-chrome jugs but are abused daily. Mine has chrome and isn't abused. I could make up OWTs about how they must be operating them, but don't. There's no data. But the results are the results.

The best looking oil and maintenance on rental engines I've seen in 25 or so years is the three airplanes owned and operated by an IA A&P. And even he had the joy of two cracked exhaust manifolds this year on the same aircraft.

It's all fairly meaningless in what are essentially 1930's air cooled tractor engines anyway. As long as they're changing he oil, it'll run. You won't find anyone who had to replace an engine because their oil was dirty or they had blow-by. (Turbos notwithstanding. You have one of those you'd better take care of it. Or one of the ridiculous high compression beasts. But an O-470? I've seen people fly them down into unbelievably low compression numbers. I wouldn't do it, but the engine doesn't care much.)
 
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