MMO to break up the sludge

OkieFlyer

OkieFlyer

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As we all know, crankcases tend to build up a little sludge over time. When I change the oil in my O-470, the new oil starts looking dirty almost immediately. I believe this is partly, if not mostly due to sludge in the low spots. I was thinking of pouring a couple quarts of Marvel Mystery Oil into the empty crankcase and letting it sit overnight to help cut the crud and help it flow out of the drain. Is there any reason I shouldn't do this? Do you think it'll help? What say you?
 
Wouldn't that just be an indication of blow-by? If you keep changing the oil on a reasonable timeframe and it never gets any cleaner...
 
denverpilot said:
Wouldn't that just be an indication of blow-by? If you keep changing the oil on a reasonable timeframe and it never gets any cleaner...
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No. That is just normal lead and other crap. My mechanic a while back said MMO is over priced solvant.
If you really want to get rid of the sludge there are two methods I have been told to try by a mechanic. Both have issues, make sure you discuss and know what you are doing with your mechanic.
1. Put avgas down the oil filler. Let it sit. Drain.
2. Leave the filler cap open and the drain spout. Put a tractor suply oil heater pad on the oil tank and let it sit overnight. The heat causes most sludge to liquify.

Tim

Sent from my LG-H631 using Tapatalk
 
tspear said:
No. That is just normal lead and other crap. My mechanic a while back said MMO is over priced solvant.
If you really want to get rid of the sludge there are two methods I have been told to try by a mechanic. Both have issues, make sure you discuss and know what you are doing with your mechanic.
1. Put avgas down the oil filler. Let it sit. Drain.
2. Leave the filler cap open and the drain spout. Put a tractor suply oil heater pad on the oil tank and let it sit overnight. The heat causes most sludge to liquify.

Tim

Sent from my LG-H631 using Tapatalk
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Wouldn't 2 happen every time you flew it? It gets hot, doesn't it?
 
denverpilot said:
Wouldn't that just be an indication of blow-by? If you keep changing the oil on a reasonable timeframe and it never gets any cleaner...
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Well, you may be right about that. Still think I have a fair amount of crud buildup in the case. I can see dirty oil on the bottom of the dipstick as soon as I add the new oil. Blow-by may be the root cause though.

tspear said:
No. That is just normal lead and other crap. My mechanic a while back said MMO is over priced solvant.
If you really want to get rid of the sludge there are two methods I have been told to try by a mechanic. Both have issues, make sure you discuss and know what you are doing with your mechanic.
1. Put avgas down the oil filler. Let it sit. Drain.
2. Leave the filler cap open and the drain spout. Put a tractor suply oil heater pad on the oil tank and let it sit overnight. The heat causes most sludge to liquify.

Tim

Sent from my LG-H631 using Tapatalk
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Yeah, the solvent in the MMO is the reason I was planning on using it. Overpriced it may be, but I already have a gallon jug of it at the house.

I have an oil heater on the oil pan already. Not sure it would get warm enough to do the trick though.
 
Are you taking your 182 around the pattern to warm the oil before you drain it? I usually do that, and our oil stays clean looking for several hours after a change.
 
I wouldn't disturb an old gunked up engine. Heard too many stories of automotive engines failing shortly after doing like procedures. Now, take a fresh overhaul engine and do that before every oil change and it may keep the gunk at bay. Back in A&P school a power plant instructor told us that most gunk was attributed to breakdown of paraffin based lubricants. My recommendation is to avoid paraffin based oils from the beginning.
 
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I have been told by several, you do not want to break up and clean out that sludge!
It is not causing any harm where it is; it likes it there. Break it up and who knows where it will end up; likely someplace bad. Definitely a case of 'It's Not Broken.....'
 
somorris said:
Are you taking your 182 around the pattern to warm the oil before you drain it? I usually do that, and our oil stays clean looking for several hours after a change.
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Yes. Takes forever to drain otherwise.

GlennAB1 said:
I wouldn't disturb an old chunked up engine. Heard too many stories of automotive engines failing shortly after doing like procedures. Now, take a fresh overhaul engine and do that before every oil change and it may keep the gunk at bay. Back in A&P school a power plant instructor told us that most gunk was attributed to breakdown of parifin based lubricants.
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Let'sgoflying! said:
I have been told by several, you do not want to break up and clean out that sludge!
It is not causing any harm where it is; it likes it there. Break it up and who knows where it will end up; likely someplace bad. Definitely a case of 'It's Not Broken.....'
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Hmm. Good points I reckon. I guess I'm just not used to oil turning dark so quickly. Bugs me a little.
 
denverpilot said:
Wouldn't 2 happen every time you flew it? It gets hot, doesn't it?
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Sure, but not as hot as you think, unless you fly it for a few hours and then change the oil. Also the oil can only hold so much, so what happens often is you get build up because there is more crud then the oil can hold. So the crud sits on the bottom, and this is bad for cooling, bad for the oil...

Tim

Sent from my LG-H631 using Tapatalk
 
Let'sgoflying! said:
I have been told by several, you do not want to break up and clean out that sludge!
It is not causing any harm where it is; it likes it there. Break it up and who knows where it will end up; likely someplace bad. Definitely a case of 'It's Not Broken.....'
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I have heard the same OWT. I have yet to actually hear of it happening to someone by name that you can ask questions.
I did the heating pad, then the avgas solution with my mechanic. Took three days/nights of avgas soaking/draining before I did not have any discoloration. We also sent the avgas down via the dipstick (Lycoming engines, mechanic said something about spashing other areas from the standard fill port). We then washed the oil pan with cheap mineral oil before refilling with regular oil.

Like I said. Discuss with your mechanic.

Tim

Sent from my LG-H631 using Tapatalk
 
just change the oil every 3 months or 25 hrs. oil is the smallest expense in owning a aircraft.
 
tspear said:
Sure, but not as hot as you think, unless you fly it for a few hours and then change the oil. Also the oil can only hold so much, so what happens often is you get build up because there is more crud then the oil can hold. So the crud sits on the bottom, and this is bad for cooling, bad for the oil...

Tim

Sent from my LG-H631 using Tapatalk
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Numerous problems scientifically with these statements.

First, I don't know of any heating pads that are going to get the oil any hotter than it is in operation unless the aircraft has an oil cooler or oil temperature regulator problem.

Second if there's "too much for the oil to hold" heating it up to lower temps than seen in flight certainly can't fix that.

And crud "sitting on the bottom" of an oil pan where little to no cooling actually takes place, making much of a significant impact on cooling seems off, too. If crud has plugged up the oil cooler, that's a different story and the proper way to clean it, isn't on the aircraft...

A solvent, I get it. But heating pads on oil pans? That one sounds like it's mostly an OWT.

Cleaning crud out of crude oil equipment in a former life required a thinner oil/solvent and scrubbing. We could heat up stuff all day and it wouldn't do anything useful other than melt the paraffin.
 
Sludge? In an aircraft engine that uses ashes dispersant oil? Not likely.

Oil discoloration comes from contaminates held in suspension. If your oil is turning color quickly I'd bet you're using a semi-synthetic oil. If the discoloration bothers you? Try an ashless dispersant mineral oil like straight weigh Aeroshell or Phillips XC.
 
Stewartb said:
Sludge? In an aircraft engine that uses ashes dispersant oil? Not likely.

Oil discoloration comes from contaminates held in suspension. If your oil is turning color quickly I'd bet you're using a semi-synthetic oil. If the discoloration bothers you? Try an ashless dispersant mineral oil like straight weigh Aeroshell or Phillips XC.
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My engine has used Aeroshell W100 straight weight for as far back as I care to look.


I guess I really shouldn't call it sludge. Just some slightly thicker residual oil containing some of the heavier contaminates. The kind of stuff that just likes to cling when the rest of it flows. Never seen a crank case that doesn't have some. Not talking about really caked on crap. Just needs a little help to get it moving. Make sense?
 
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Might sound odd, but we've never had any serious discoloration of the oil until way too many hours are on it.

That said, whatever is in CamGuard makes the oil seem like it has a lot more "surface tension" for lack of a better way to describe it. And when we started using it the oil flowed more freely but "stuck to" things better, and came out a lot more consistently the same color. It also seemed to lighten it significantly over time.

That's all completely unscientific, and it took a couple of oil changes to get there, but our oil on the dipstick looks "fabulous" to this guy used to black-as-soot oil from his diesel tractor and truck, and even looks better than the cars. And I change oil on all of those often. Maybe even too often.

CamGuard adds a touch of a "yellow" sheen to fresh oil and it "clings" to the dipstick better. No idea why, I'm no chemist. For all I know it's snake-oil, but with folks recommending it for any engine that might sit, as ours does *occasionally*, we use it.

This post is as OWT as any other offered but the stuff seems to be good is all I can say.
 
Texas Skyways does a sump mod on big Continentals to get that last little bit of oil out. I've seen it and never thought much about it. If I drain my oil right after flying it flows out quickly and I don't think what's left in there is a threat to the clean 10 quarts I'll add.
 
denverpilot said:
Numerous problems scientifically with these statements.

First, I don't know of any heating pads that are going to get the oil any hotter than it is in operation unless the aircraft has an oil cooler or oil temperature regulator problem.

Second if there's "too much for the oil to hold" heating it up to lower temps than seen in flight certainly can't fix that.

And crud "sitting on the bottom" of an oil pan where little to no cooling actually takes place, making much of a significant impact on cooling seems off, too. If crud has plugged up the oil cooler, that's a different story and the proper way to clean it, isn't on the aircraft...

A solvent, I get it. But heating pads on oil pans? That one sounds like it's mostly an OWT.

Cleaning crud out of crude oil equipment in a former life required a thinner oil/solvent and scrubbing. We could heat up stuff all day and it wouldn't do anything useful other than melt the paraffin.
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No idea on the science, but the heating pad did get stuff to drain out that had not come out before.

Tim
 
I didn't see it mentioned, but by chance does this engine have chromed cylinders?
 
My best automotive oil change was when I did it twice. After reading numerous articles and internet threads about oil viscosity, I decided to put 10W40 in my car that requires 5W20. I left the 10W40 in for less than one day. At normal operating temperature the 10W40 registered a whole needle width hotter. Was that because the heavier weigh had a thicker film on the temp bulb? Don't, know. Didn't like it. Changed the oil back to 5W20. Now, that 5W20 stayed cleaner longer than any other oil change. I remember checking my oil before a trip a couple months later and thinking that I should do that every oil change (but with cheaper throw away oil).
 
denverpilot said:
Might sound odd, but we've never had any serious discoloration of the oil until way too many hours are on it.

That said, whatever is in CamGuard makes the oil seem like it has a lot more "surface tension" for lack of a better way to describe it. And when we started using it the oil flowed more freely but "stuck to" things better, and came out a lot more consistently the same color. It also seemed to lighten it significantly over time.

That's all completely unscientific, and it took a couple of oil changes to get there, but our oil on the dipstick looks "fabulous" to this guy used to black-as-soot oil from his diesel tractor and truck, and even looks better than the cars. And I change oil on all of those often. Maybe even too often.

CamGuard adds a touch of a "yellow" sheen to fresh oil and it "clings" to the dipstick better. No idea why, I'm no chemist. For all I know it's snake-oil, but with folks recommending it for any engine that might sit, as ours does *occasionally*, we use it.

This post is as OWT as any other offered but the stuff seems to be good is all I can say.
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I've used Camguard in the last few oil changes. I don't care if it's snake oil or not. My plane does have a tendency to sit for a couple weeks at a time with my work schedule, and gets flown in spurts. I feel better with the Camguard in there.

Yeah, my oil turns pretty dark within a few hours, which I could live with. What I'd like to get rid of is the obvious residual black oil already on the dipstick immediately after filling with fresh oil, before ever starting the engine. I feel like if I can actually get all the old stuff outta there for once, I can actually see how much of the contamination is from the engine, or blow-by. If I'm starting with halfway dirty oil everytime, I just can't tell if I really have a problem or not.

I'm actually going to switch to Phillips XC for the first time, and see if there is any kind of difference versus the W100.




GlennAB1 said:
My best automotive oil change was when I did it twice. After reading numerous articles and internet threads about oil viscosity, I decided to put 10W40 in my car that requires 5W20. I left the 10W40 in for less than one day. At normal operating temperature the 10W40 registered a whole needle width hotter. Was that because the heavier weigh had a thicker film on the temp bulb? Don't, know. Didn't like it. Changed the oil back to 5W20. Now, that 5W20 stayed cleaner longer than any other oil change. I remember checking my oil before a trip a couple months later and thinking that I should do that every oil change (but with cheaper throw away oil).
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That was actually my very first thought. Just do another oil change after an hour or two. It's basically just flushing or "rinsing" it with clean oil, and draining it out before an new contaminates build up. Given the high price of aviation oil, I got to thinking maybe just sort of "rinsing" the oil pan with MMO would maybe achieve the same thing using something I had lying around. Did the same thing with my old Chevy 305 inboard boat engine a few years ago. The oil barely even gets dirty between oil changes now.
 
denverpilot said:
Or... it just cooked a layer of oil? :)

Dunno man... seems odd.
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Lol, nope to cooking. There was chucks and jello like crap in the drain pain. Ever see the cloudy stuff on your oil dipstick or cap? That is what it looked like.
I know the cloudy stuff is caused by water vapor, but we have now hit my knowledge limit.

Tim

Sent from my LG-H631 using Tapatalk
 
Alright, I went ahead and left a quart of MMO in the oil pan last night. Drained it out this morning and it was black as the ace of spades. Dumped in a quart of Phillips XC and immediately drained it. It was dirty, but it was not as bad. Quite a bit of particulate (non-metallic) flowed out throughout the draining. Dumped in another quart of MMO and let it sit for a while then drained it again. A little bit of particulate came out initially, but it was fairly pure MMO by the end. I feel like I got the junk out of the bottom of the pan for once. Went ahead and filled with fresh oil and some camguard. For the first time after an oil change, there is no visible black shiznit on the dipstick. Now we'll see if it makes any difference in how long it takes to turn it dark again. Might not have done anything good, but at least I know the new oil isn't going to be immediately contaminated by stuff left in the pan. When it comes to crap, I say better out than in.
 
A gallon of diesel fuel would have done the same thing for a lot less money!
 
Stewartb said:
A gallon of diesel fuel would have done the same thing for a lot less money!
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Yup. Or some solvent. I've done that. It gets some residual stuff out. Put it in, rock the airplane around enthusiastically, drain it out quick. The location of the drain makes a big difference; some aren't right at the lowest point in the airplane's usual attitude.

But much of the black one soon sees after a change comes from dirty oil that didn't leave the engine. The oil cooler holds a bunch. Some have drain plugs, and many don't. Some have drain caps halfway up the cooler; a fat lot of good they do. The engine's oil galleries remain at least partly full of dirty oil during an oil change. The constant-speed prop has some dirty oil in it. The nose of the crank behind the CS prop has a layer of thick, awful crud inside it after several hundred hours; it's flung outward and glued to the wall of the bore by centrifugal force. You wouldn't want that stuff coming loose and going back through the governor. Nasty. It takes some time with a custom-made scraper to peel it off and pull it out when changing a prop.
 
Stewartb said:
A gallon of diesel fuel would have done the same thing for a lot less money!
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Told ya, I already had MMO laying around the house. It was like $10 per gallon and I used about 2 quarts. Didn't want to go buy some diesel just for that purpose. I'll probably be okay. ;)
 
Before the 1950-60's, most automotive engines did not have oil filters, like many aircraft engines. The engines and oil used were designed for the solid particulate in the oil to fall out of suspension and build up in the sump so that is was no longer circulating through the oil system. Sludge buildup was normal and expected. With the advent of oil filters, things like detergents and dispersants were added to the oil to keep the particulates in suspension so that they could go through the oil filter and be trapped there. That said, the most likely reason oil changed darker soon after an oil change, is simply some of the old oil doesnt drain and mixes with the new oil. Oil changes typically only drain whats in the sump, not what also in the oil lines, oil coolers, internal oil passages, pockets in the heads/rocker boxes, etc. As another post mentioned, if you really want to see perfectly clean oil after a change, change it twice with a a short run up in between.
 
My case of oil turning black after just a few hours turned out to be bad rings causing blow by... the fix wasn't cheap but worked.
 
I don't want to do one of those copy cat threads, but I have the opposite problem (/fortune?).
My IO-520 has about 250 hours on it. I have had the oil changed every 25-30 hours since I bought it with ~50 hours on it. Come oil change time, it is down to about 10 qts and still looks relatively clean.

Either my engine is very clean or the oil isn't doing it's job of cleaning out whatever sludge or blow by may be there.

Am I just worrying too much? I have often heard that if the oil doesn't get dirty it isn't doing it's job.
 
My 0-520's oil looks pretty clean when drained, too. My compressions are all high-70s so little blowby, as evidenced by very little breather dripping. I'm happy!
 
My parents had a twin diesel boat. GM 6V53s. Back then, alternative uses were in city busses and gen sets. Tough duty cycles, each in their own way.

We ran them at full tilt boogie in cruise, which like on airplanes, is most of the time. The oil was black as coal, and after an oil change, the new oil was black as coal in minutes. Yes we had - and changed - filters every oil change. I guess the filters got the really big chunks out. :dunno: But there had to be a lot of old oil that wouldn't drain out.

2000 hours and beyond a few plugged injectors, they were trouble free.

Don't worry about the dark oil.

-Skip
 
I change my oil every 50 hours and its never been black. It's been a dark greenish gray color every time. To the guy who asked about chrome cylinders, I have chrome cylinders in mine. Just wondering why the question.
 
Timbeck2 said:
I change my oil every 50 hours and its never been black. It's been a dark greenish gray color every time. To the guy who asked about chrome cylinders, I have chrome cylinders in mine. Just wondering why the question.
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There's folks who will say they're not as good and will cause excessive blow by. On the opposite front, many recommend them for airplanes that sit between flights.

We have 'em too, didn't choose them, last owner did, but with the airplane not always getting flown every week, they're the right thing for the job.
 
I started to use MMO on the last flight before oil change, it seems to help with morning sickness, but it's too early to tell.
If you want to get sludge out, I've heard pour some gas in after draining the oil, let it sit overnight and drain the next day.
 
denverpilot said:
There's folks who will say they're not as good and will cause excessive blow by. On the opposite front, many recommend them for airplanes that sit between flights.

We have 'em too, didn't choose them, last owner did, but with the airplane not always getting flown every week, they're the right thing for the job.
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Higher oil consumption, oil turning black quickly, and more blowby are common traits of chrome cylinders.

You won't ever hear me say having chrome cylinders is a good thing whether or not the engine sits for long periods of time. There are plenty of other things in an engine to rust in a dormant engine and cylinders are some of the easier/cheaper things to deal with.
 
mondtster said:
Higher oil consumption, oil turning black quickly, and more blowby are common traits of chrome cylinders.

You won't ever hear me say having chrome cylinders is a good thing whether or not the engine sits for long periods of time. There are plenty of other things in an engine to rust in a dormant engine and cylinders are some of the easier/cheaper things to deal with.
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Yep we hear that all the time and have little oil consumption, little to no blow-by, and clean oil at 1000 hours.

So it's filed in the OWT category for now for us.
 
denverpilot said:
Yep we hear that all the time and have little oil consumption, little to no blow-by, and clean oil at 1000 hours.

So it's filed in the OWT category for now for us.
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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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