How much oil burn is too much?

deyoung

deyoung

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Chris
I realize that oil consumption may vary quite a bit, but I want to get an idea of what the acceptable range is and when (absent any other signs of a problem) I should start to care?

Lycoming O-540-B4-B5, currently I usually add a quart maybe every 4 or 5 hours of flight time, give or take. Seems a little high, but no other signs of issues; compressions all in the mid-70s. Last oil analysis showed just slightly high iron but otherwise nothing noteworthy; next one coming shortly.

Thoughts? Thanks!
 
That doesn’t seem unreasonable for an o-540. I fly and maintain several airplanes with 540s (a total of 7 engines) and they all seem to consume a quart of oil in 4-8 hours. The worst consumer is an Aztec used for training so it has a harder life than the others. Of interesting note, the engine that consumes the least oil is the highest horsepower turbocharged engine.
 
Something else to consider...how full is full? As in, what's the oil level after you add a quart? How about after 5 hrs run time? After 10 hrs? If you fill your sump, your gonna blow a bunch of oil out the breather. In my (very) limited experience, there aren't any engines that will run with a "full" sump without blowing a bunch of oil out the breather.
 
Eric Lehto said:
there aren't any engines that will run with a "full" sump without blowing a bunch of oil out the breather.
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As with so many topics in life, "none, all; always, never" is not appropriate or accurate.
 
yup.....let it get down to 5-6 qts....then tell me how long it takes to use a quart.
 
Lycoming publishes a max limit on oil consumption.
 
That doesn't sound unreasonable to me. My IO-360 burns around a quart every 5 hours on average, although less as the quantity gets closer to 6 quarts as others have noted above.

From the Operators Manual, it looks like the max consumption on the O-540-B is somewhere between 0.78 and 0.67 quarts per hour.

O-540 Oil Consumption Limits.jpg

https://www.lycoming.com/sites/default/files/O & IO-540 Oper Manual 60297-10.pdf page 3-10
 
CMongoose said:
From the Operators Manual, it looks like the max consumption on the O-540-B is somewhere between 0.78 and 0.67 quarts per hour.
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Based on that Chris, I'd say you're good to go.


BTW - got your name right this time. ;)
 
mondtster said:
That doesn’t seem unreasonable for an o-540. I fly and maintain several airplanes with 540s (a total of 7 engines) and they all seem to consume a quart of oil in 4-8 hours. The worst consumer is an Aztec used for training so it has a harder life than the others. Of interesting note, the engine that consumes the least oil is the highest horsepower turbocharged engine.
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Turbocharging discourages oil consumption. The cylinder, except at low power, doesn't experience negative pressures during the intake stroke as an NA engine does, so oil isn't drawn past the rings and valve guides so much.

I looked after one 540, NA, and I don't remember it using that much oil. Break-in procedure is critical to limiting oil consumption, as is not filling the sump to the max if doing so tends to drop the oil level a lot within a very few hours after that fillup.
 
In a 540 with compressions in the 70s and 6 quarts of oil you should use a quart every 10-20 hours.
 
Are you burning the quart or blowing it out,due to overfilling.
 
Dan Thomas said:
Turbocharging discourages oil consumption. The cylinder, except at low power, doesn't experience negative pressures during the intake stroke as an NA engine does, so oil isn't drawn past the rings and valve guides so much.

I looked after one 540, NA, and I don't remember it using that much oil. Break-in procedure is critical to limiting oil consumption, as is not filling the sump to the max if doing so tends to drop the oil level a lot within a very few hours after that fillup.
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Cylinder pressures are relative, but I get your point. Horsepower, number of cylinders, bore size, cylinder finish, and piston/ring package are just some of the other contributing factors to oil consumption (I’ve done quite a bit of consumption testing).

All the 540s I’ve been around used oil at a rate greater than one quart in 10 hours regardless of who broke them in (including factory run-ins) and having a reasonable amount of oil in the engine. That’s just been my experience with them, right or wrong.
 
I find that for my IO-470, with 12qt spec, I will lose a quart very quickly if I fill it up. 10 quarts is the sweet spot. 9 is the lowest recommended. I put a quart in once we get down to 9 from 10, which is about 8-10 hours.
 
I generally don't let it get below 9, so maybe I'm blowing off more than I'm burning, though I don't notice too much of a mess. Just got the analysis back, which looks normal, though lots of phosphorous - I'll have to look up what that means.
 
No, but I've only recently started doing analysis regularly, so I don't really have trend data yet. I use Aeroshell W-100+. The lab didn't seem worried about it, so I won't either for now. :)
 
deyoung said:
Thoughts?
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I've found that most aircraft engines have a sweet spot for oil levels. Fill above that spot and it gets rid of the "extra" oil every time. Sometimes its it's by engine model, sometimes by individual engine, or both. On a PA-31 with TIO-540s, we ran the L/H engine a quart low and the R/H two qts low. Even turbine engines are the same way. On one particular turbine helicopter we ran them with oil levels just above the minimum mark on the sight glass as anything above that ended up on the tailboom at the end of the day.
 
Bell206 said:
I've found that most aircraft engines have a sweet spot for oil levels. Fill above that spot and it gets rid of the "extra" oil every time. Sometimes its it's by engine model, sometimes by individual engine, or both. On a PA-31 with TIO-540s, we ran the L/H engine a quart low and the R/H two qts low. Even turbine engines are the same way. On one particular turbine helicopter we ran them with oil levels just above the minimum mark on the sight glass as anything above that ended up on the tailboom at the end of the day.
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I wonder if the canting of the engines had something to do with it.

I also imagine the flight attitudes of different planes and pilot habits in climb, cruise, and descent play a role too, relative to how the oil lays in the sump during those states of flight.
 
455 Bravo Uniform said:
I wonder if the canting of the engines had something to do with it.
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Quite possible. On occasion it was how a person read the dip stick. The same dip stick was used for the LTIO/TIO and had 2 scales engraved on it. So if you read the wrong scale by side, it created an "induced" problem. Eventually we would grind off the dip stick scale not applicable to engine it was installed.
 
The oil capacity on my IO520 is 12 quarts. I put in 10 and a pint of Camguard. I burn a quart about every 23-25 hours. If I put in 12 it winds up on the belly.
 
You numbers fall in line with the acceptable oil burn. On my Cherokee 6, we filled it to 10 quarts and it promptly blew 2 quarts out.

We run it at 8 quarts and no lower than 6 quarts. Normal flight for us is 5.6 hours and we generally add a quart then.
 
How much oil burn is too much?

Enough so that you will drop below the minimum before the flight is over.
 
I fill my O-360 to 8 quarts at oil change and typically hit 50 hours before it gets below 6. Before the overhaul it was burning a quart every 5 hours.
 
The Lycoming recommendations allow for a ridiculous amount of oil usage for acceptable operation. So you can apparently operate safely, but I would start to investigate if it gets to more than a quart every 4 hours. BTW, you can have excellent compressions and still have shot oil control rings. BTDT. My old O-320 went through a quart every 6-8 hours. (The new one hardly uses a quart every 20 hours.) If you start getting blowby (quickly blackening oil) or periodic oil fouling on lower plugs, I'd be looking to find a fix. The oil is going somewhere: it's either going out the breather or going out the exhaust. If the latter, it could be building deposits where you don't want them. As others have mentioned, some engines are better oil misers if they are not filled to capacity.The O-235-C2C and O-320-E2G engines I've owned preferred to be filled one quart below capacity. If filled to that level, I get the maximum number of hours per quart. I add oil when it gets to 2 quarts below capacity. The O-320s seem really happy running between 6-7 quarts out of 8 max, even when new. Oil usage in and of itself is not necessarily a problem. Combined with other issues, it could be a sign of needed maintenance.
 
pigpenracing said:
I wouldn't run a 12 quart capacity 540 with 5 quarts :confused:
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why?....it will do just fine with much less. Why do you think it was certified to 12?

§ 23.1011 General.
....
(b) Each engine must have an independent oil system that can supply it with an appropriate quantity of oil at a temperature not above that safe for continuous operation.
(c) The usable oil tank capacity may not be less than the product of the endurance of the airplane under critical operating conditions and the maximum oil consumption of the engine under the same conditions, plus a suitable margin to ensure adequate circulation and cooling.
.....
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Checkout_my_Six said:
why?....it will do just fine with much less. Why do you think it was certified to 12?
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The more oil the cooler the oil temp will run and the cleaner the oil will stay.....
I would run a 540 with 9-10.
Not 5 :confused:
Maybe I take care of my engines better?
 
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