Losing 1 QT Per Hr

[V1VRV2]

I started losing oil at an alarming rate. IO550G in an Ovation. About 870 hrs. I changed my oil the other day and added 8 quarts ran the motor and did a leak check. Then topped it off with an additional quart. Showed 8 on the dipstick. Flew for 3.8 hrs. Rechecked oil 2 days after landing and I was 3 quarts low. Showing 5 on the dipstick. Previous to the oil change I did a compression check. All cylinders were 60-70. The exhaust pipes are not oily. Top plugs were inspected and five of the plugs were clean. and one was a little bit oil fouled. But not bad. I didn’t pull the bottom plugs. Engine run up and mag check is normal. No unusual loss of RPM. Belly is clean on the pax side. Dirty on the pilot side. Pilot side is where the crank case breather is located. I’m having a hard time believing this oil is being burned in the cylinders. Any ideas? Valve guide?

Edited August 10, 2023 by V1VRV2

[DXB]

Maybe a broken ring? Look for scores on cylinder wall with the oily top plug (which is never normal)?

[hubcap]

I actually saw something about this recently. I don’t recall the details, but someone had an issue where the oil was being kept from returning to the reservoir where the dipstick measured. It was hit or miss, but if you search the forum you should find it. It wasn’t using the oil. The oil was still in the engine but the dipstick wasn’t reading it.

[Pinecone]

I had an issue with my 252 with losing about a quart an hour.  In my case, after flight it was dripping off the tail tie down.

Shop on my field, based on a similar issue, flushed the air/oil separator and the hose from the left front to the right rear where the separator is located.

Whatever, it solved the issue.

I have also heard of the issue that hubcap mentioned

 

[Bolter]

14 minutes ago, hubcap said:

I actually saw something about this recently. I don’t recall the details, but someone had an issue where the oil was being kept from returning to the reservoir where the dipstick measured. It was hit or miss, but if you search the forum you should find it. It wasn’t using the oil. The oil was still in the engine but the dipstick wasn’t reading it.

You could drain the oil and measure the volume, and verify the dipstick reading if there was doubt.  In my former IO360 in a J, when my consumption jumped to 1 qt/hr, it was a broken oil ring, and there was nothing unusual on the belly or unique with that cylinder with the borescope or  compression checks.  My point is that you may find indications of a broken ring with inspection but cannot eliminate a broken ring based on inspection.  -dan 

[Fly Boomer]

1 hour ago, V1VRV2 said:

I started losing oil at an alarming rate. IO550G in an Ovation. About 870 hrs. I changed my oil the other day and added 8 quarts ran the motor and did a leak check. Then topped it off with an additional quart. Showed 8 on the dipstick. Flew for 3.8 hrs. Rechecked oil 2 days after landing and I was 3 quarts low. Showing 5 on the dipstick. Previous to the oil change I did a compression check. All cylinders were 60-70. The exhaust pipes are not oily. Top plugs were inspected and five of the plugs were clean. and one was a little bit oil fouled. But not bad. I didn’t pull the bottom plugs. Engine run up and mag check is normal. No unusual loss of RPM. Belly is clean on the pax side. Dirty on the pilot side. Pilot side is where the crank case breather is located. I’m having a hard time believing this oil is being burned in the cylinders. Any ideas? Valve guide?

Start with the Vividia VA-400 Version 5 (high resolution).  If you don't have one, get the Wi-Fi box so you can use it with iPhone or iPad.  If you don't see anything wonky in the cylinders, move on to more complex speculation.

[LANCECASPER]

3 hours ago, V1VRV2 said:

I started losing oil at an alarming rate. IO550G in an Ovation. About 870 hrs. I changed my oil the other day and added 8 quarts ran the motor and did a leak check. Then topped it off with an additional quart. Showed 8 on the dipstick. Flew for 3.8 hrs. Rechecked oil 2 days after landing and I was 3 quarts low. Showing 5 on the dipstick. Previous to the oil change I did a compression check. All cylinders were 60-70. The exhaust pipes are not oily. Top plugs were inspected and five of the plugs were clean. and one was a little bit oil fouled. But not bad. I didn’t pull the bottom plugs. Engine run up and mag check is normal. No unusual loss of RPM. Belly is clean on the pax side. Dirty on the pilot side. Pilot side is where the crank case breather is located. I’m having a hard time believing this oil is being burned in the cylinders. Any ideas? Valve guide?

The IO550 and the TSIO550 both like to play tricks on you when you check the oil. Make sure it is level and check it again the next day. On an Ovation I had I checked it a couple hours after I landed and I was alarmed that it was at 5, the next morning it was at 7.5. Unless you see any other signs I'd still keep an eye on it, but I wouldn't lose sleep yet based on everything you verified.

[Little Dipper]

I could comment but for now am all ears.   Interesting post.    

[toto]

4 hours ago, V1VRV2 said:

I started losing oil at an alarming rate. IO550G in an Ovation. About 870 hrs. I changed my oil the other day and added 8 quarts ran the motor and did a leak check. Then topped it off with an additional quart. Showed 8 on the dipstick. Flew for 3.8 hrs. Rechecked oil 2 days after landing and I was 3 quarts low. Showing 5 on the dipstick. Previous to the oil change I did a compression check. All cylinders were 60-70. The exhaust pipes are not oily. Top plugs were inspected and five of the plugs were clean. and one was a little bit oil fouled. But not bad. I didn’t pull the bottom plugs. Engine run up and mag check is normal. No unusual loss of RPM. Belly is clean on the pax side. Dirty on the pilot side. Pilot side is where the crank case breather is located. I’m having a hard time believing this oil is being burned in the cylinders. Any ideas? Valve guide?

Similar thing just happened to me, but I was burning a quart every 15 minutes. The cylinders had just been compression tested, with a 78/80 reading on what turned out to be the problem child. Compression rings were in perfect shape but the oil control ring had broken. You could pour oil out of the bottom plug after just a few minutes of running.

Anyway, based on my very recent experience, you might be looking at an oil control ring.

ETA: In my case, the belly was clean and the exhaust showed no significant oily residue either.

 

[dzeleski]

I’ve had higher oil consumption twice. Once was due to the crankcase oil air separator slipping in its mount apparently causing it not to drain properly and pulling more oil out then normal. Second time was a cracked head drain tube, but this left a giant mess in my cowl, on the nose gear, and all over the belly. We traced it by cleaning the engine really well and then running it. 
 

Is the oil getting black faster?

As others have said though a borescope and pulling the bottom plugs will probably say a lot.

[V1VRV2]

Thanks for the replies. I have a mechanic coming out to look at it next week. The oil has 3.8 hrs on it and looks much darker than it should for that little time in use. We are starting to believe it’s a broken oil control ring. I will report back once I know.

[Jeff Uphoff]

On 8/10/2023 at 9:54 PM, LANCECASPER said:

The IO550 and the TSIO550 both like to play tricks on you when you check the oil. Make sure it is level and check it again the next day. On an Ovation I had I checked it a couple hours after I landed and I was alarmed that it was at 5, the next morning it was at 7.5. Unless you see any other signs I'd still keep an eye on it, but I wouldn't lose sleep yet based on everything you verified.

I've seen this same musical-dipstick game when checking my IO-550 oil shortly after a flight. It appears to really need time to settle back down to get a good reading, and ramp slope seems to have a noticeable effect on the reading as well.

Would love to hear the ins and outs of the above observation(s) from any A&P(s) in the know.

[Schllc]

I didn’t notice big variations in dipstick readings on my two ovations. But I can tell you it has been something I expect with acclaims, and have noticed the issue on all of the ones I have owned.

[Steve Dawson]

I've noticed that the oil takes at least a couple days to drain back with my 231 and it was similar on my J. So if the oil stays up in the engine and doesn't make it back to the sump area does the engine actually have enough oil for proper lubrication when you're climbing to altitude or even when cruising? I'm making the assumption that the oil pick up is close to the location of the dipstick. 

[A64Pilot]

The min bearing safe limit for oil level is a really stupid low level, meaning our engines both Lyc and Conti can at least for a short time operate with a very low oil level.

Don’t quote me because this memory is about 20 years ago, but min oil level is about 2 quarts. Do not of course ever let it get that low.

Once running the oil level certainly drops but of course that’s by design meaning wherever it is when running is the proper level.

‘Many years ago I remember the 30 and 60KW generators in the Army, they had markings on the stick for both sitting and running and they were very different

[Fly Boomer]

1 hour ago, A64Pilot said:

The min bearing safe limit for oil level is a really stupid low level, meaning our engines both Lyc and Conti can at least for a short time operate with a very low oil level.

Don’t quote me because this memory is about 20 years ago, but min oil level is about 2 quarts. Do not of course ever let it get that low.

Once running the oil level certainly drops but of course that’s by design meaning wherever it is when running is the proper level.

‘Many years ago I remember the 30 and 60KW generators in the Army, they had markings on the stick for both sitting and running and they were very different

I thought I read once that these engines had to be able to run indefinitely with fifty percent of the specified oil capacity.  That said, I can hardly remember what I had for breakfast.

[RoundTwo]

Do you use Camguard? If so, it takes a lot longer for the oil to drip down off of the internals and checking oil level shortly after flying will yield lower perceived oil levels.

[Pinecone]

On 8/12/2023 at 9:42 PM, Fly Boomer said:

I thought I read once that these engines had to be able to run indefinitely with fifty percent of the specified oil capacity.  That said, I can hardly remember what I had for breakfast.

What I recall is that the certification standard is that the max level had to be at least 2x the minimum level.  So if the minimum is 4 quarts, the max needs to be at least 8 quarts.

[M20F]

Oil is going to go one of three places.  Out the breather and the belly will be coated.  Out the case and the cowling will be coated.  Out the exhaust and the exhaust pipe will be oily/coked.  Find where the oil is going and that will answer the question.  

[V1VRV2]

Pulled the bottom plugs today. No oil contamination. Exhaust is clean. No oil. The only source of the oil on the belly has to be coming from the breather. Why would the crankcase be pressurizing? 

[Ragsf15e]

20 minutes ago, V1VRV2 said:

Pulled the bottom plugs today. No oil contamination. Exhaust is clean. No oil. The only source of the oil on the belly has to be coming from the breather. Why would the crankcase be pressurizing? 

Busted rings cause blowby.  Or the “lined up” rings.  You may still get compression checks ok because oil “seals” the bottom of the cylinder but you still get excess blowby.  Good luck finding it!

[blaine beaven]

14 hours ago, Pinecone said:

What I recall is that the certification standard is that the max level had to be at least 2x the minimum level.  So if the minimum is 4 quarts, the max needs to be at least 8 quarts.

On the 0-540 I flew, it had a minimum oil level of 3qts. 

[EricJ]

5 hours ago, V1VRV2 said:

Pulled the bottom plugs today. No oil contamination. Exhaust is clean. No oil. The only source of the oil on the belly has to be coming from the breather. Why would the crankcase be pressurizing? 

Even with zero blowby (which I think is not typical) the crankcase is venting pressure as you climb to thinner air, so aerated oil will be going out the vent just because of the change in pressure with altitude.

Some blowby is normal, and even a little bit will keep the crankcase at higher pressure than the ambient air, so aerated oil will be going out the breather at some steady, if even very slow, rate.

[N201MKTurbo]

I had an engine once that answered a few of these questions. I was completing a flight from Durango CO back to Denver. When the prop started to surge. I checked the oil pressure and the needle was swinging full scale. 
 

So the first indication that you don’t have enough oil is the prop will lose control. It isn’t subtle, it will get your attention. 
 

I shut the engine down and dead sticked into a dirt strip. After landing I checked the oil and just barely on the dip stick. The next day I had a friend drive me out to the plane and it took 6 Qts to get it to 8, so it had 2 quarts of oil when the oil pressure started to fluctuate. I ran the engine up for 15 min (the time to fly home) and it used a quart. I topped it off and flew it home.

The next day I pulled the plugs and did a compression check. The plugs looked fine and all the compressions were good. One cylinder had a drop of oil on its intake tube, so I decided to pull it. When I pulled the cylinder off, a piece of the piston fell on the floor. It was the metal between the oil ring and the second ring and about 1/3 of the way around the piston. 
 

I replaced the piston and rings and it worked fine after that. That cylinder still had that drip on the intake pipe after fixing it, so I was just lucky pulling that one.

[jlunseth]

22 hours ago, M20F said:

Oil is going to go one of three places.  Out the breather and the belly will be coated.  Out the case and the cowling will be coated.  Out the exhaust and the exhaust pipe will be oily/coked.  Find where the oil is going and that will answer the question.  

Or out the quick drain. Had the joy of that experience once, causing an emergency landing in Canada. Small fragment of plastic was caught in the quick drain seal. Oil loss got progressively worse of a couple of months. Little or no oil on the belly until the final episode.