O360 - What's your average oil consumption?

[bcg]

I've got a 63 C with the O360-A1D, it's got roughly 1900 SMOH and I'm using .28 of a quart, or 9 oz, per hour. My flying is about 25% pattern work and 75% traveling, average fuel burn is just over 9GPH. This is averaged over the 62 hours I've had the plane.

 

What are you guys seeing? I think this is pretty reasonable and indicates a fairly healthy motor but, I've got no real frame of reference.

 

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[BrianWilkins]

So basically you're using a quart every 4 hours.  That seems kinda high to me, but then again you're just about to TBO.  

[kerry]

What oil level do you keep in your sump. I try to maintain 5-6 quarts.  My understanding is anything above 6 quarts ends up on the belly.

[bcg]

What oil level do you keep in your sump. I try to maintain 5-6 quarts.  My understanding is anything above 6 quarts ends up on the belly.

5-6, I've found that if I go over 6 it blows it out almost immediately.

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[PT20J]

What oil are you using? Depending on where the oil is going, some report that straight weight burns less and some find that multi-vis burns less. It's worth a try to switch and see if it changes. 

[PT20J]

BTW, I had an IO-360 for seven years that got 4-4.5 hours per quart the whole time I had it. If the engine is running fine, I would not be concerned about it, unless it suddenly increases.

[bcg]

What oil are you using? Depending on where the oil is going, some report that straight weight burns less and some find that multi-vis burns less. It's worth a try to switch and see if it changes. 

Phillips XC 20W-50. That's what the previous owner was using and I didn't see any reason to change with the hours where they are. I'm using Camguard as well

It runs great since I fixed the bad plug wire, very smooth and reliable.

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[Shadrach]

5 minutes ago, bcg said:

Phillips XC 20W-50. That's what the previous owner was using and I didn't see any reason to change with the hours where they are. I'm using Camguard as well

It runs great since I fixed the bad plug wire, very smooth and reliable.

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I run the same oil but in an IO360.  My burn is about half of yours but temps and mission (pattern work vs cruise) seem to affect burn rate a bit.  I’m at mid time but have nearly perfect compression readings.  I would not worry about it, but it would be nice to know where it’s going.  Is the belly covered? 

[bcg]

I run the same oil but in an IO360.  My burn is about half of yours but temps and mission (pattern work vs cruise) seem to affect burn rate a bit.  I’m at mid time but have nearly perfect compression readings.  I would not worry about it, but it would be nice to know where it’s going.  Is the belly covered? 

There's some film in the bottom of the engine compartment but, nothing I would consider abnormal for any engine compartment. I've not noticed oil on the belly but, haven't specifically looked for it. I'll check tomorrow morning during preflight.

I do use less oil in cruise, we made a 16.5 hour round trip to Ga in September and used about 3 quarts.

I'm not really concerned, just curious about what others see. Compression was checked in August and they were all mid 70s.

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[Hank]

My C runs ~9 gph, maybe 8-1/2 at 9000msl or higher. Oil burn starts off ~10 hr/qt right after a change, and rises to 5-6 hrs/qt at 50 hrs. Ballpark numbers for the last 15 years.

[MikeOH]

IO-360A1A, 2600 SMOH, compressions all in the high 70s, burns 1 qt/7-8 hrs.  I never fill over 6 qts.  FWIW I run LOP at 65%

[cliffy]

O-360   950 hrs   @9-10 hrs / qt at 6 qts full.   9500  WOT 2500RPM  ROP leaned

[carusoam]

O360 experience…

1) 10hrs / qt… kind of a rule of thumb…

2) New oil does last longer than 50hr or 80hr old oil….

3) Over filling the oil, shows up dripping off the tail tie down ring…

4) leaky or damaged oil control ring… shows up on the lower spark plug in that cylinder…  engine monitors are helpful here.

5) There are a dozen possible places for external oil leaks… but leaky a quart out of the engine is going to be really messy…

6) big oil ring problems are usually pretty obvious… bubbly, exhaust smelling, black oil are a hint…

7) Consistent measuring technique is important…

8) Long X-Cs… don’t use much oil…

9) Pattern work… uses more than expected…

10) High power and climb attitude has a tendency to let oil escape…

11) Compare to an IO550… very little oil disappears in 10hrs… and it’s color doesn’t change as much…

12) Find where it is going….

(I have only had two IO550s… both were newer than my O360… not much statistical value implied with my data…)

PP thoughts only, not a mechanic…

Best regards,

-a-

 

[Hank]

OK, here's some real data.

We picked up a puppy over Christmas, from the same breeder we got our last dog from. He lived 14-1/2 great years, and we decided after several months that we wanted another one. My inlaws were halfway to furthest WV, and we flew into horrible headwinds coming home. 

We stayed low for the puppy, alternating between 4500 and 6500, hoping for lower wind. Seems we were between 95 and 105 knots groundspeed, while indicating 135 mph. The flight stretched to almost exactly 4 hours, and I filled up with 34 gallons, for a real 8.5 gph. I was at either 22"/2400 at 4500msl or 21"/2500 at 6500, although I stayed VFR and ducked under some clouds south of Rome, GA down to less than 4000 msl (at 3500, I reset power to 23"/2300).

Going up, we were showing 153-155 knots at 8000msl, 21"/2500, but I don't remember how much we topped off with--I was distracted by a puppy and a canceled credit card just because there were two declined purchases for $1900+ of Prada which neither my wife nor I wear . . . .

[DXB]

It's airworthy and acceptable just based on that consumption value alone.  However, it's worth considering where the oil is going - is there oily residue on the exhaust pipe?  Most likely not - it's probably on the belly. If the oil turns black pretty quickly (within 10 hrs of change) that's diagnostic for high ring blowby pushing oil mist out the breather.  Then the question is whether it is simply the crosshatch being polished out on all 4 cylinders (highly plausible at 1900 SMOH) or is there evidence of one offending cylinder (e.g. stuck oil control ring which may leave you with pooled oil in the cylinder and an oily top plug and /or a broken compression ring which may show up as deep scores on the sidewall when you borescope). Having a ton of oil accumulating in one cylinder can increase detonation/pre-ignition risks.  

One may not be too enthusiastic to rework a cylinder at 1900 SMOH under these conditions unless anything looks dangerous, just for the sake of decreasing oil consumption.  

For comparison I've put 1100 hrs on the same engine as yours in the last 8 years of ownership ,and it's at 1600 SMOH, but overhaul was back in 2000.  I've done lots of cylinder work in that interval.  Best oil consumption I've seen is ~1qt/9hr, now it's down to it's worst at 1qt/3hr.  The most problematic seems to be #4, which does oil up the top plug even though I replaced it only 200 hrs ago.  A ring flush had no effect.  I think my engine is perfectly safe for now but may just overhaul it rather than do more cylinder work if it goes much higher.

[bcg]

1 minute ago, DXB said:

It's airworthy and acceptable just based on that consumption value alone.  However, it's worth considering where the oil is going - is there oily residue on the exhaust pipe?  Most likely not - it's probably on the belly. If the oil turns black pretty quickly (within 10 hrs of change) that's diagnostic for high ring blowby pushing oil mist out the breather.  Then the question is whether it is simply the crosshatch being polished out on all 4 cylinders (highly plausible at 1900 SMOH) or is there evidence of one offending cylinder (e.g. stuck oil control ring which may leave you with pooled oil in the cylinder and an oily top plug and /or a broken compression ring which may show up as deep scores on the sidewall when you borescope). Having a ton of oil accumulating in one cylinder can increase detonation/pre-ignition risks.  

One may not be too enthusiastic to rework a cylinder at 1900 SMOH under these conditions unless anything looks dangerous, just for the sake of decreasing oil consumption.  

For comparison I've put 1100 hrs on the same engine as yours in the last 8 years of ownership ,and it's at 1600 SMOH, but overhaul was back in 2000.  I've done lots of cylinder work in that interval.  Best oil consumption I've seen is ~1qt/9hr, now it's down to it's worst at 1qt/3hr.  The most problematic seems to be #4, which does oil up the top plug even though I replaced it only 200 hrs ago.  A ring flush had no effect.  I think my engine is perfectly safe for now but may just overhaul it rather than do more cylinder work if it goes much higher.

There's no oil on the exhaust pipe or the belly.  When we pulled the plugs to clean them about 30 hours ago, there was some buildup on the bottom plugs in #1 (had a bad wire so wasn't working) and #3.  #1 was pretty badly fouled but, that's to be expected with a bad wire.  #3 was just moderate, more than the others, not so bad that it was preventing it from firing.

[PT20J]

350 hrs on IO-360 factory rebuilt. Compression high 70s. Using Phillips X/C 20w50. Gets 12 hrs/ qt with new oil and 9-10 hrs after 50 hrs.  I usually run between 6 and 7 qts. Tried 5-6 and didn’t notice any difference in consumption or oil on belly. 

[Rjfanjet]

My O360 has 1100SMOH and 500STOH. The engine overhaul was done in 1987, top in 2007. I've been averaging 70 hours a year since I bought her in June 2019. 1 qt\12 hours. Oil analysis is fantastic and so are compressions, all 78 or above. Switched to Phillips Victory 20W50 two changes ago. I add 7 quarts with the filter change. When the quantity gets below 6, I add a quart.

[Ragsf15e]

4 hours ago, bcg said:

There's no oil on the exhaust pipe or the belly.  When we pulled the plugs to clean them about 30 hours ago, there was some buildup on the bottom plugs in #1 (had a bad wire so wasn't working) and #3.  #1 was pretty badly fouled but, that's to be expected with a bad wire.  #3 was just moderate, more than the others, not so bad that it was preventing it from firing.

Couple observations… good compressions indicate the valves working well, but could still have a blowby issue past rings.  That area can be “sealed” with oil giving good compressions.  The evidence will be along the left side of the belly behind your breather.  Look closely at the belly under the pilot seat.  Even with some blowby, that’s not necessarily terrible.  Just gotta wash the belly and add some oil.

What type cylinders do you have?  What color is the stripe on them?  Is the hatching still on the cylinder walls?

i use about 6hrs/qt.  I’ve been as low as 3 when I was having some cylinder issues.  Money and a new cylinder fixed that.  1300hr engine 1998 OH, chrome cylinders.

 

[larryb]

My mid time IO 360 used a quart every 4 to 5 hours during the 5 years I owned it. More during IFR training and less during my normal cross country usage.

[Greg Ellis]

This is from the Lycoming Break In Service Instruction.  Not sure if this is the calculation used to see if your oil use has stabilized during Break In or if it is general formula for max allowable oil consumption anytime but it is a guide I suppose to see how the engine is doing.  They were a little vague in the SI on its application.

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

[DXB]

16 hours ago, bcg said:

There's no oil on the exhaust pipe or the belly.  When we pulled the plugs to clean them about 30 hours ago, there was some buildup on the bottom plugs in #1 (had a bad wire so wasn't working) and #3.  #1 was pretty badly fouled but, that's to be expected with a bad wire.  #3 was just moderate, more than the others, not so bad that it was preventing it from firing.

Most will have some oil on the belly behind the breather tube exit from the left cowl flap - it's a matter of how much appears and how fast after cleaning it off - so a bit subjective.  How fast the oil turns black is more objective.  There are also means of measuring crank case pressure - perhaps the most objective when measuring blowby but rarely done. Also it's not the standard fouling with combustion byproducts including lead we're talking about.  The plugs get wet with oil when the oil control ring doesn't do its job.  Some oil on a bottom plug is common and not necessarily abnormal.  Seeing oil on the top plug is another story.

[bcg]

1 minute ago, DXB said:

Most will have some oil on the belly behind the breather tube exit from the left cowl flap - it's a matter of how much appears and how fast after cleaning it off - so a bit subjective.  How fast the oil turns black is more objective.  There are also means of measuring crank case pressure - perhaps the most objective when measuring blowby but rarely done. Also it's not the standard fouling with combustion byproducts including lead we're talking about.  The plugs get wet with oil then the oil control ring doesn't do its job.  Some oil on a bottom plug is common and not necessarily abnormal.  Seeing oil on the top plug is another story.

Right now, I'm 32.5 hours since my last oil change and the oil is still golden and clear on the dipstick, I've added a total of 8qt oil and 1 qt Camguard (I put one in every 6 qt of oil) over the last 32.5 hours.  I haven't seen it turn black yet but, with that much fresh oil being added, I'd be very surprised if it did.  I did my first oil change at 30 hours and it looked almost like new in the bucket with no metal in the filter, just one little piece of carbon in.  I need to ask them if they've gotten the results of the oil analysis back yet, it's been about 2 months since we changed the oil so they should have it soon, if they haven't gotten it yet.

[Hank]

41 minutes ago, bcg said:

Right now, I'm 32.5 hours since my last oil change and the oil is still golden and clear on the dipstick, I've added a total of 8qt oil and 1 qt Camguard (I put one in every 6 qt of oil) over the last 32.5 hours.  I haven't seen it turn black yet but, with that much fresh oil being added, I'd be very surprised if it did.

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 . . . .

[DXB]

40 minutes ago, bcg said:

Right now, I'm 32.5 hours since my last oil change and the oil is still golden and clear on the dipstick, I've added a total of 8qt oil and 1 qt Camguard (I put one in every 6 qt of oil) over the last 32.5 hours.  I haven't seen it turn black yet but, with that much fresh oil being added, I'd be very surprised if it did.  I did my first oil change at 30 hours and it looked almost like new in the bucket with no metal in the filter, just one little piece of carbon in.  I need to ask them if they've gotten the results of the oil analysis back yet, it's been about 2 months since we changed the oil so they should have it soon, if they haven't gotten it yet.

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