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Normal Oil Burn?

Prepperpilot

Well Known Member
Been doing some longer xc flying recently. O360 700hrs TT on engine.
Seems like I add 1 qt every 10-11hrs. That about right? Oil Temps pretty steady at 170F.
Thanks
 
Yep that's not out of line at all. I usually add about 1.5 qts for a 25 hour period. I know some people that are less and some that are more. I like my oil temps around 180-185 too.

Where do you normally keep your oil level? That can have a big impact on how much oil a guy adds.
 
OIL

That is well within tolerance BUT. My 0 320 will use less than 1 quart in 20 hours. Factory Lycoming nitride cylinders.
Try running the oil level at 6 to 6 1/2 quarts. Add 1/2 quart at a time.
That should make a noticeable improvement.
170 oil temperature is too low. 180 minimum.
 
Be happy I burn one in 5 with a 550 hour channel chrome 0-360 cs prop. and SDS fuel and ignition.
But I've heard worse. You're good to go.
I try to keep oil temps up, But, It's hard sometimes, even with the cooler closed off.
Oh ya I fill with 6 1/2 on change with filter. Burn to 4 1/2 quarts add one repeat. Till I change again.
Art
 
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170 oil temperature is too low. 180 minimum.

Where did 180 minimum come from?
165-220 is the recommended range from Lyc.
Some documents even state 140 min for continuous operation.
 
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Thanks friends. Generally don't like to over fill. Try to keep at 7qts. Seems to happy there. If I bring it to 8 seems to blow out.
 
Oil Temperature

180 is the minimum from many sources for decades as the minimum temperature to eliminate moisture.
 
Lycoming-oil-temps.jpg
 
0IL TEMPERATURE

I am not questioning Lycomings numbers. The chart states DESIRED temperature above ambient 30 F is 180 F. Most of Lycoming's numbers for the popular normally aspirated engines have not changed in 50 years. Some slight changes in oil pressure limits.
 
The vapor pressure of water increases by a factor of roughly 2.5 between 140F and 180F implying that 2.5 times as much water could get carried out of the crankcase vent with the blow-by gasses at the higher temperature
 
Suggest you run at 6 qts instead of 7. You might see 12 or 13 hrs per qt instead of 10.

That is interesting. About your suggestion.. I was concerned if I get to 6 qts or below. I did notice previously that it seemed to stay there longer at 6. But nervous a about getting too low. Perhaps I will see if that's the case when I head back from MYR to CMH.
Stupid question also. Is there a minimum from Lycoming?
 
Rehearsed subject…
Yes, the OPs oil burn is normal. Normal? Define normal please. If that means between nil and highest, you‘re pretty good :)

Re the other popcorn subject, aka oil Q at refill, I usually pour 5 qts + a couple oz of Camguard. Monitor the burn, add as needed, easy no?
 
Interesting

What is interesting is the minimum safe oil quantity stated by Lycoming is only 2 quarts. I would never test that though.
 
Oil

The six quarts for minimal oil consumption and 2 quarts for absolute minimum is for most parallel valve 320/360's with eight quart sump. IO 360 angle valve will require more oil for most sumps.
 
Where did 180 minimum come from?
165-220 is the recommended range from Lyc.
Some documents even state 140 min for continuous operation.

Thanks Walt. The books seem to be mere guidelines to so many folks.
 
180 is the minimum from many sources for decades as the minimum temperature to eliminate moisture.

Probably the same source that has said for decades that you can't run lean of peak and oil must be at 100* for take off.

For decades they have been telling pilots to prime a carb by pumping the throttle before starting. We KNOW this is a bad idea, but it is STILL recommended by most CFI's.

The fact that something has been repeated for decades, doesn't make it accurate.

Larry
 
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That is interesting. About your suggestion.. I was concerned if I get to 6 qts or below. I did notice previously that it seemed to stay there longer at 6. But nervous a about getting too low. Perhaps I will see if that's the case when I head back from MYR to CMH.
Stupid question also. Is there a minimum from Lycoming?

I had a marked improvement filling to 5 adding at 4 on my -390. Min need to operate is 2 qts.
 
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My IO-360-M1B really seems to like 5.5 qts as its happy spot.

Carl you beat me to it about the M1B. I hear that 2 qts min as a blanket statement and there are a lot of people here running the M1B. Although even if I could go to 2 qts I wouldn't have the balls to come anywhere close to that. :D
 
Pesky Physics

The vapor pressure of water increases by a factor of roughly 2.5 between 140F and 180F implying that 2.5 times as much water could get carried out of the crankcase vent with the blow-by gasses at the higher temperature

Thanks for providing an objective reason for running these engines at the "desired" temperature. I know some very respected engine builders who suggest we target 200F for this very reason.
 

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I had a marked improvement filling to 5 adding at 4 on my -390. Min need to operate is 2 qts.
I was told by Lycoming of absolute minimum of 3.5 qts for the IO390-EXP119 which has a smaller sump (7qts max)
If memory serves me right, 4 qts was the minimum for my last IO390 which had a 8qts max sump.
 
I was told by Lycoming of absolute minimum of 3.5 qts for the IO390-EXP119 which has a smaller sump (7qts max)
If memory serves me right, 4 qts was the minimum for my last IO390 which had a 8qts max sump.

Gotcha - Maybe the factory can chime in as see if they are still running 5 adding at 4 on their -EXP119
 
$- jets seem to thermostat to run over 212 degrees F/100 C.

Though synthetic- I think it keeps the water content as low as possible.

Someone can correct me, but our oil temp is measured at its coolest point and sees about 35 degrees F rise in circulation.

That gets the water out each pass, and combustion continually adds water vapors.

Not sure if cool oil impacts its short life in aviation, but water during hangar life sounds negative.

If 180 was not "right" why the Vernatherm action there and not 140 or 212?
 
thank you. I believe you are correct

$- jets seem to thermostat to run over 212 degrees F/100 C.

Though synthetic- I think it keeps the water content as low as possible.

Someone can correct me, but our oil temp is measured at its coolest point and sees about 35 degrees F rise in circulation.

That gets the water out each pass, and combustion continually adds water vapors.

Not sure if cool oil impacts its short life in aviation, but water during hangar life sounds negative.

If 180 was not "right" why the Vernatherm action there and not 140 or 212?

thank you I believe you are correct
 
Originally Posted byjrs14855 View Post
170 oil temperature is too low. 180 minimum.

Originally posted by Walt:
Where did 180 minimum come from?
165-220 is the recommended range from Lyc.
Some documents even state 140 min for continuous operation.


Just to be clear, I was not implying that 180 isn't a desirable temp, but there's nothing wrong if it's at 165 or 220.
I just don't like it when folks make "factual" statements that 170 is too low and it has to be 180, that implies something is wrong when it's not.
 
$- jets seem to thermostat to run over 212 degrees F/100 C.

Though synthetic- I think it keeps the water content as low as possible.

Turbines don't have an oil sump exposed to combustion gases, water cannot be introduced into the oil system from turbine section like an internal combustion engine.
 
Pumping the Throttle

Article by Paul Dye July 5, 2017 Kitplanes advocated pumping the throttle is fine as long as the engine is is turning over with the starter.
I agree with this completely. Further there are Lycoming powered airplanes with engines that only have the mechanical primer plumbed to two cylinders. In that case pumping the throttle is more efficient because it provides fuel to all cylinders.
On my carburated 0 320 I prime with the throttle most of the time. I engage the starter with the throttle fully closed. If it doe's not fire on the second blade I quickly push the throttle about 1/4 open and then back to near closed. The engine starts immediately at any ambient temperature above 40 degrees.
DO NOT prime by pumping the throttle before engaging the starter.
Regarding oil temperature, Lycoming says that when the engine will take full throttle without stumbling it is ok for takeoff regardless of oil temperature. In other words Lycoming has no minimum oil temp for takeoff with normally aspirated engines.
 
Have just been reading this thread with interest and both JRS and Larry have posted saying not to prime with throttle unless the engine is cranking. Could either of you kindly expand on this for educational purposes, please? Is the risk related to fire?
 
Priming

Priming a updraft carburetor equipped engine with a Marvel carb-if the throttle is pushed all the way to the stop this dumps an incredible amount of fuel, most of which will end up in the air box. Very likely to start a fire if the engine does not start. A short pump of approximately 1/4 throttle travel will provide what seems to be the correct amount of fuel for a four cylinder Lycoming. With the starter engaged most of the fuel will go to the cylinders.
My recent experience with this has been in temperatures of 40 degrees F or slightly above. 50 or above I make a first attempt with throttle at idle no pumping. This procedure is only for float carbs. Fuel injection and pressure carbs are different.
 
I love VAF, but it is very frustrating to read threads where the question is about normal oil burn and it turns into recomended starting procedures. - Start a new thread.

On the oil burn issue, I think the real question should be about "safe" oil burn.
"Normal" oil burn should be very low. like 1qt per 30 to 40 hours. If a brand new engine is not broken-in properly it could burn 1qt every 5 hours. That would be perfictaly safe (as long as you dont run it out of oil).
What is important is knowing your engine. Know where the oil burn is comming from. If it is comming from the valve stems then you have a problem that justifies some work.
 
A Cessna 150 that over primed.
 

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The maximum oil consumption on my engine (O-360-A1A) is .78 quarts per hour - per Lycoming. That is a quart of oil every 1.3 hours. This number is for airframers when selecting an engine for their airplanes - Cessna, Piper, Beechcraft,……. and you (since you are the airframer). The goal here is to not let oil consumption to be the limiting limitation on range as advertised by the airframer. At .78 qts/hr, my 8 Qt oil sump, with a 2 Qt minimum safe limit should last 7.6 hours. This (in most cases) exceeds the fuel quantity range limit on most certified GA airplanes. Does Lycoming think you should be flying around with only 2 quarts of oil? I don’t think so, but you can safely do it if your other primary oil limitations (pressure and temperature) are within limits. Do they recommend filling the oil sump to 8 quarts? I don’t think they would recommend that either. But they built their sump to hold enough oil so that max range at max oil consumption would exceed max range of the airframe at normal fuel consumption. That’s how they sell engines to Cessna, etc. They don’t sell an engine to Cessna, they sell a fleet. It’s a big deal.
How does that affect what we do? We are the airframer, and even if we didn’t build it, we can dictate the way we operated our engines. We decide how much oil we are willing to add to the crankcase when we change the oil, and how low we are willing to let it go. Lycoming’s minimum RECOMMENDATION (for us EAB guys) is 2 quarts, maybe more for you, if we choose to comply with that recommendation. Personally, I put in 7 quarts during an oil change, because nothing pukes out at that level in my airplane as long as I’m not inverted. When my oil level drops below 5 quarts, I add one unless I’m getting close to an oil change, and then I don’t. I typically change my oil every 25-35 hours, and don’t need to add any between oil changes.
 
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My problem is blow-by. Not sure that is included in the definition of oil burn. My consumption depends upon power settings. 5 hr/qt at 70% power and 9 hr/qt at 55% power.
 
Lycoming’s minimum RECOMMENDATION (for us EAB guys) is 2 quarts, maybe more for you, if we choose to comply with that recommendation.

Just wanted to add that the minimum oil quantity for the Lycoming IO-360-M1B (and some other variants) is 4 quarts.

i-PXKvCRk-XL.jpg
 
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My problem is blow-by. Not sure that is included in the definition of oil burn. My consumption depends upon power settings. 5 hr/qt at 70% power and 9 hr/qt at 55% power.

A good quality air oil separator will prevent a good portion of that oil from being expelled over board.
 
MY TITAN IO-375

I have a Titan IO-375 (360 high compression) with 425 hours TT. I'm trying to find the right oil level so I can reduce my oil consumption (1qt/4 hours). I've been using the range 6 1/2 - 5 1/2 range but it's still using oil. Suggestions include taking that range to 5 1/2 - 4 1/2 , but I just don't have the balls to do that! Compression on all cyl are good and no oil leaks visible. I DO have to wash the bottom of my RV-7 frequently. I typically run it at %70 & 23"/2500.
Thoughts?
 
FWIW,
I have a IO-375-M1, 9:1 pistons and the only time it has more than 5 qts is when I change the oil and pour in 6 qts.
At 6 and above, I noted a rapid loss of oil quantity even for a short flight.

At 5 1/2 or less, I lose 1 qt / 13 hours approx.
If the projected flight is short, ~1 hour or less, I can depart at 4 and a tad above. Never below 4.
If the flight is longer, I usually top it off to 5.
Engine seems happy with that...
 
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