O360 - What's your average oil consumption?

[DXB]

On 1/15/2023 at 10:04 AM, Hank said:

Good Lord! I hope that 9 qts. in 32.5 hours includes the 7 quarts you added as the oil change! Otherwise you're looking at less than 4 hours/quart. That much oil loss / byrn would worry me. If you've truly added 9 quarts since your oil change, it's still golden honey colored because there's not much old oil left . . . .

Not true. 3.5 hrs/qt is airworthy, not dangerous in and of itself if cause is blowby.  That is identical to my current oil consumption, and I add the same amount. My oil turns and stays black after 10 hours or so despite the added oil.  

[Utah20Gflyer]

My engine uses a quart every 5-6 hours.  I have chrome cylinders which I understand use oil faster on average than non chrome cylinders.  

[bcg]

1 hour ago, DXB said:

Oil only gets out 3 ways - blown out the breather, consumed in combustion, leaking out directly.  If you were leaking that much oil it would be ridiculously obvious.  If the oil is not black after 30hrs then it's not likely to be blowby, even with dilution with the added fresh oil (in comparison - I add the same amount of oil as you and my oil turns black by10 hours and stays black until I change it at 30hrs. In your case, that leaves oil consumed by combustion.  In this situation Mike Busch would tell you to use your borescope to look at the intake valve stems. If they are oily, then oil is getting sucked into the combustion chamber on the intake stroke from the rocker box. The fix for that is changing the intake valve oil seal, which is straightforward.

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2014-02_high-oil-consumption.pdf

 

I'll see about pulling the plugs again and running a borescope in at the next oil change, it wouldn't hurt to clean and regap them then anyway. 

 

I'm of 2 minds about this.  On the one hand, it's a high time engine that's running well other than oil consumption on the high side and a losing some oil through combustion isn't really that big a deal, especially since my fuel burn is in line with what it should be, so I don't know that I really want to dig into it to fix something that isn't really broken.  Lycoming's formula works out to an acceptable oil consumption of .58qt per hour and I'm not there.  On the other hand though, if it's something that can be fixed relatively simply without getting too intrusive into the motor, then it's probably worth doing to save some money on oil and Camguard.

 

I'll talk to them about it when we do the next oil change, take a peek with a borescope and get their input on it.  I'm not really worried about it right now, the previous owner says my consumption is pretty much in line with what he was seeing for the couple of years he had it and he did do a couple of cylinder overhauls during that time, so it's not a new thing.  If it's been like this for a couple of hundred hours, it's probably not really hurting anything.

[skykrawler]

Is it true that Lycoming's have intake oil seals?  I don't think they do.

[carusoam]

If all the oil is going to one cylinder…

The lower spark plug is at risk of getting crusted over in oil crust…

With an engine monitor… you can see one cylinder always giving you a hard time on the one plug…

This might be an oil ring not working properly…. 
 

The good part… oil rings are pretty easy to swap out…

PP thoughts only…

-a-

[DXB]

8 minutes ago, skykrawler said:

Is it true that Lycoming's have intake oil seals?  I don't think they do.

Great point - my brief search indicates they do not.   Can anyone else comment on how the OP might be getting high oil combustion without also getting a lot of blowby? It seems like the main mechanism would be burning oil that the oil control ring fails to clear.  Or could oil come through a trashed valve guide? I'm at the limit of my largely Mike Busch-derived knowledge here.

16 minutes ago, bcg said:

I'll see about pulling the plugs again and running a borescope in at the next oil change, it wouldn't hurt to clean and regap them then anyway. 

 

I'm of 2 minds about this.  On the one hand, it's a high time engine that's running well other than oil consumption on the high side and a losing some oil through combustion isn't really that big a deal, especially since my fuel burn is in line with what it should be, so I don't know that I really want to dig into it to fix something that isn't really broken.  Lycoming's formula works out to an acceptable oil consumption of .58qt per hour and I'm not there.  On the other hand though, if it's something that can be fixed relatively simply without getting too intrusive into the motor, then it's probably worth doing to save some money on oil and Camguard.

 

I'll talk to them about it when we do the next oil change, take a peek with a borescope and get their input on it.  I'm not really worried about it right now, the previous owner says my consumption is pretty much in line with what he was seeing for the couple of years he had it and he did do a couple of cylinder overhauls during that time, so it's not a new thing.  If it's been like this for a couple of hundred hours, it's probably not really hurting anything.

Yeah agree nothing to go crazy over. It would be nice to figure out which mechanism of oil loss predominates in your case though - I'm not sure I get it yet. 

[bcg]

1 minute ago, carusoam said:

With an engine monitor… you can see one cylinder always giving you a hard time on the one plug…

You keep saying things like this...

It was my plan to put an EDM900 in this plane but the King GPS decided it wanted to be replaced first and used that budget up.  Maybe in another 6 months or so I'll do the engine monitor, it would be nice to get rid of all the legacy gauges and have everything in one place.

 

[DXB]

1 minute ago, bcg said:

You keep saying things like this...

It was my plan to put an EDM900 in this plane but the King GPS decided it wanted to be replaced first and used that budget up.  Maybe in another 6 months or so I'll do the engine monitor, it would be nice to get rid of all the legacy gauges and have everything in one place.

 

One other thought - check the routing of your breather tube - they should go up for a bit before being routed down. There may be other positioning issues that increase oil escaping. That would explain oil exiting a case that's not pressurized and oil that doesn't turn black from blowby

[carusoam]

13 minutes ago, bcg said:

You keep saying things like this...

It was my plan to put an EDM900 in this plane but the King GPS decided it wanted to be replaced first and used that budget up.  Maybe in another 6 months or so I'll do the engine monitor, it would be nice to get rid of all the legacy gauges and have everything in one place.

 

I’ve been a fan of instrumentation on machinery since the 80s….

For airplanes… after my first 10hrs of airplane ownership…

As far as affording an engine monitor… it took me a decade for that…. 

• one half for engine monitor
• Other half for monitor installation 

 

Things working in our favor…

There are a selection of really nice pre-flown engine monitors that have come up for sale lately… even if they are not primary…

They didn’t really become widely used until the mid 90s… so there aren’t tons of them…

A good relationship with your mechanic… you can do a lot of the wiring/installation with their oversight…

If this is your forever-plane… you get the chance to add cool instruments over time…

 

 

Sooooooo many things to consider…. There are no perfect answers….  
 

Best regards,

-a-

[bcg]

3 minutes ago, carusoam said:

I’ve been a fan of instrumentation on machinery since the 80s….

For airplanes… after my first 10hrs of airplane ownership…

As far as affording an engine monitor… it took me a decade for that…. 

• one half for engine monitor
• Other half for monitor installation 

 

Things working in our favor…

There are a selection of really nice pre-flown engine monitors that have come up for sale lately… even if they are not primary…

They didn’t really become widely used until the mid 90s… so there aren’t tons of them…

A good relationship with your mechanic… you can do a lot of the wiring/installation with their oversight…

If this is your forever-plane… you get the chance to add cool instruments over time…

 

 

Sooooooo many things to consider…. There are no perfect answers….  
 

Best regards,

-a-

This isn't the forever plane, long term my plan is a 252 or a Bravo, I want that turbo and 10 more inches of space.  That's what slows down some upgrades, it's a lot easier to justify spending money just because I want it when I'm planning to keep the plane forever. 

I've thought about installing a non-primary monitor but there are a couple of reasons I don't want to go that route.  First, my panel is super cluttered and there really isn't any room for one.  More importantly though, it's the same amount of work to install a primary as it is to install a secondary so I might as well do the primary in the beginning. 

I do have a great relationship with my mechanic, those guys are the best.  I figure it would probably take me about 40 - 50 hours to put a system in, the wildcard is how much time it takes to pull all the old stuff and wiring out.  I'll probably have to replace the panels as well, or at least the right side.  It's all that which really slows me down.  Some things on their own aren't that big a deal but, when you think about all the other stuff that will be required, it starts to turn into a much larger project.  I'd love to replace my old Icarus SAM GPSS and the CDIs with a 2nd G5 as well but, that also cascades into much more work that turns what should be a 4 - 5 AMU project into a 10 AMU project pretty quickly...

 

[M20F]

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2014-02_high-oil-consumption.pdf
 

Remember Mike Busch is one of the most quoted people here except anything the peanut gallery feels very strongly they are smarter than him on.  

[A64Pilot]

On 1/15/2023 at 11:39 AM, DXB said:

Great point - my brief search indicates they do not.   Can anyone else comment on how the OP might be getting high oil combustion without also getting a lot of blowby? It seems like the main mechanism would be burning oil that the oil control ring fails to clear.  Or could oil come through a trashed valve guide? I'm at the limit of my largely Mike Busch-derived knowledge here.

Yeah agree nothing to go crazy over. It would be nice to figure out which mechanism of oil loss predominates in your case though - I'm not sure I get it yet. 

I have never seen valve guide seals on an airplane, don’t know why though, it would seem logical?

You get lots of oil through the guides when they wear. The rocker arm imparts a side load and over time this causes wear, and wear will of course allow oil through, from both the intake and the exhaust.

My guess is his cylinders are just well used and oil is being used from everywhere, not just one place, past the rings and the valves, as well as blow-by.

I’d start saving for an overhaul myself, not saying it needs it now but it’s coming.

Ran a compression test on a neighbors C-182 yesterday, he had just bought it, flown 34 hours so far, said it had flown 150 hours in the last ten years and had two cylinders at 70. 250 hours since major but many years ago.

He said it flew 15 hours a year for ten years regular as clockwork according to the book.

Well I conducted the test and only two are at 70 now, one was as low as 30ish, but if I let the prop move until I was having to fight it, it would go up to 70.

Borescope showed excessive pitting from rust in all cylinders and one cylinder has the vertical scrape marks that could come from broken rings, on top so not wrist pin.

It’s an IO-540, he uses 1 gt every 6 hours, all valves were sealed, no detectable leak, but of course the blow-by was so bad you could blow out a match from the dip stick tube.

My bet is the aircraft sat for years and someone pencil whipped the book to make it look that it had an Annual every year and divide the time between years is why it flew 15 hours every year.

Every plug was clean, engine makes good power, cruises at 140+ kts and climbs at 1500 FPM, starts easily etc. Except for an oily belly no indication at all of very low compression.

I believe you can only bore Lycoming cylinders .010 and I don’t think his would clean up, he’s ordering 6 new ones as there are none available now I don’t think. I told him to shorten his oil change interval to 25 hours and let’s do a compression check and borescope then just to monitor what’s going on.

Its my belief that blow-by influences cams being eaten up, blow-by is acidic and the cam is directly in line to get the blow-by on it, and shortening oil change interval may help.

Thats my theory anyway.

[bcg]

Interestingly, I had a 3 hour XC round trip on Friday, we used about .3 quarts of oil on that. I haven't really tracked consumption in the pattern vs XC closely but, if this is any indication, then pattern work is using a lot more oil than just flying is.

Sent from my Pixel 6a using Tapatalk

[A64Pilot]

On 1/15/2023 at 10:12 AM, DXB said:

Not true. 3.5 qts/hr is airworthy, not dangerous in and of itself if cause is blowby.  That is identical to my current oil consumption, and I add the same amount. My oil turns and stays black after 10 hours or so despite the added oil.  

Do you have a reference for that? Because I don’t believe that’s Lycomings guidance. Lycoming has a formula. 

NOTE
The following formula is used to calculate the maximum allowable oil consumption limits for all
Lycoming aircraft engines.
0.006 x BHP x 4 ÷ 7.4 = Qt./Hr.

If I do the math right and check my math as I do make mistakes, that’s .65 quarts an hour max. for a 200 HP engine.

https://www.lycoming.com/sites/default/files/Lycoming Reciprocating engine Break-In and Oil Consumption.pdf

On 1/18/2023 at 3:01 PM, bcg said:

Interestingly, I had a 3 hour XC round trip on Friday, we used about .3 quarts of oil on that. I haven't really tracked consumption in the pattern vs XC closely but, if this is any indication, then pattern work is using a lot more oil than just flying is.

Sent from my Pixel 6a using Tapatalk
 

High power like taking off and climbing increases the cylinder pressure greatly (it has to, that’s where the power comes from) the higher the pressure, the more the blow-by.

I believe and this is my opinion only, but Lycomings max allowable burn is at cruise power. .1 qt per hour is nothing, personally I’ve never owned a Lycoming with oil consumption that low, even one I overhauled that had compressions of 80/80.

[phxcobraz]

Just tested this over the past week on my O-360, as I noticed my oil getting black after 15hrs or so, even with adding new. Did 1hr Wednesday and 6.2hrs round trip on Saturday and total oil burn is around 1/2-3/4qt. So I would say about 8hr/qt. Using Phillips 100AW. I bought some 20-50XC to try out next change, as it has been colder than normal in AZ this winter.

400hr SMOH  

Cruise average is around 9gph 21.5/2450

Edited January 24, 2023 by phxcobraz

[amillet]

680 hours on factory rebuilt IO-360.  Filled to 8 quarts last oil change. 20 hours later down to 6 quarts. 10 hours/ quart

[Dubs]

After solving 3 oil leaks, my engine is dry after 30 hours. With 2500 SMOH but all cylinders being replaced at some point, current oil consumption is a quart every 9 hours.

[DXB]

On 1/20/2023 at 8:06 AM, A64Pilot said:

Do you have a reference for that? Because I don’t believe that’s Lycomings guidance. Lycoming has a formula. 

NOTE
The following formula is used to calculate the maximum allowable oil consumption limits for all
Lycoming aircraft engines.
0.006 x BHP x 4 ÷ 7.4 = Qt./Hr.

If I do the math right and check my math as I do make mistakes, that’s .65 quarts an hour max. for a 200 HP engine.

https://www.lycoming.com/sites/default/files/Lycoming Reciprocating engine Break-In and Oil Consumption.pdf

High power like taking off and climbing increases the cylinder pressure greatly (it has to, that’s where the power comes from) the higher the pressure, the more the blow-by.

I believe and this is my opinion only, but Lycomings max allowable burn is at cruise power. .1 qt per hour is nothing, personally I’ve never owned a Lycoming with oil consumption that low, even one I overhauled that had compressions of 80/80.

oops typo - meant 3.5hrs/qt, not the inverse... which is consistent with the formula

[bcg]

We've done some maintenance recently and I've learned a few things that I thought I would come back and add for context.

The first is that I have chrome cylinders, which I think at least partially explains my oil usage being a little on the high side.  I discovered this when I cleaned the plugs, I went ahead and bore scoped the cylinders and valves while the plugs were out because it was convenient and I have a bore scope.  Valves all looked really good and the cylinders were in good shape with just a little bit of carbon on a couple of them.

The other thing is that I did have a little bit of oil on the belly when we did the brakes last week.  It's the first time I've really looked for that (I kept forgetting to) so I don't know how long it took for it to build up.  I wiped it all down and will keep an eye on it to see how quickly the film returns and get a feel for how much I'm losing out the breather.

The exhaust pipe doesn't have any oily residue in it and the oil that came out when we changed it looked pretty clean, not brand new clean but, not black.  Filter had some carbon in it and we sent a sample off to have a look at it.  Last sample showed chrome on the high side at 6ppm but, now that I know the cylinders are chrome that makes perfect sense.

Funny thing is that a couple of weeks ago I flew from Prescott back to Kerrville and only used about .75 qt in the 6 hour flight.  We flew about 3 hours this week from Kerrville to CC and back, I haven't checked the oil again after that trip.  It'll be interesting to see where it is and if that last flight was an anomaly or the start of a new trend.  I'm less worried about it suddenly using less oil than it has been but, at the same time I always get a little concerned when a trend changes because there has to be a reason.

[A64Pilot]

I wouldn’t worry too much about changing oil consumption. Check level before every flight of course and keep oil in it, carry extra oil and a funnel,  but don’t get worried unless consumption makes a big increase, often a decrease can be attributed to there being more oil in there than realized, hasn’t been long enough for it all to drain down.

It can be high if you fill it to 8 qts until it throws out the excess, it can be high flying patterns and short trips too, and it can drop down quite a bit on a longer flight, particularly if not flown at full throttle.

Hot weather seems to increase it some too.

These things are designed to burn oil, it’s normal and desirable, up to a point of course and that point is a lot of oil.

Oh, and it’s not at all uncommon for oil consumption to decrease on an airplane that used to sit a lot once it gets flown frequently again after some number of hours.

Edited July 9, 2023 by A64Pilot

[bcg]

I wouldn’t worry too much about changing oil consumption. Check level before every flight of course and keep oil in it, carry extra oil and a funnel,  but don’t get worried unless consumption makes a big increase, often a decrease can be attributed to there being more oil in there than realized, hasn’t been long enough for it all to drain down.
It can be high if you fill it to 8 qts until it throws out the excess, it can be high flying patterns and short trips too, and it can drop down quite a bit on a longer flight, particularly if not flown at full throttle.
Hot weather seems to increase it some too.
These things are designed to burn oil, it’s normal and desirable, up to a point of course and that point is a lot of oil.
Oh, and it’s not at all uncommon for oil consumption to decrease on an airplane that used to sit a lot once it gets flown frequently again after some number of hours.

The guy I got this plane from put about 100 hours on it in a year. I've put 150 on it in the last 11 months. This girl doesn't sit much, maybe a couple of weeks every now and again but it usually flies at least once a week. In the last couple of months, they've all been 3+ hour XC flights, with a couple of exceptions.

Sent from my Pixel 6a using Tapatalk

[Ragsf15e]

23 hours ago, bcg said:

The guy I got this plane from put about 100 hours on it in a year. I've put 150 on it in the last 11 months. This girl doesn't sit much, maybe a couple of weeks every now and again but it usually flies at least once a week. In the last couple of months, they've all been 3+ hour XC flights, with a couple of exceptions.

Sent from my Pixel 6a using Tapatalk

 

I also have chrome cylinders.  I’ve had the airplane about 10 years now, and I get ~6 hours/qt.   It did drop once when I had some cylinder/valve issues, but I had the cylinders OH’d due to the chrome flaking off and oil consumption went back to 6. The breather will spit your thin film on the belly which is normal.  Also, I only fill to 6 qt.  Never more as it comes out faster.