Oil consumption vs hours

[AlexPeterson]

As I approach 1000 hours on my plane/engine, I am curious about what to expect regarding oil consumption. My engine has been fairly consistent in oil consumption, about one quart per 8 to 10 hours. Should one expect the consumption to increase noticably as the hours pile on, or are there too many variables to predict? My only long term experience with engines prior to this plane has been with cars, and I've found them to consume oil (if at all) at a constant rate during the life, with little change.

What say those of you with lots of hours on individual airplane engines?

Thanks -

[jeff beckley]

I do not think there is a constant. I have 100 hours on my lyc rebuild and other than a quart used in the first 10 hours I have not used more than 1/2 quart in the last 90 hrs. A lot of how much oil is consumed I believe is in how the engine is broken in, Quality of cylinder rebuild, and how full you keep your levels.
My 0-360 calls for 8 qts. No way I put that much in. It only blows out right away to 6.5 qts and stabilizes.
My buddy was always complaining about the quart per 8 hour rate he was using.
He would check his stick and when he saw it was down to 6.5 qts he added a quart. I suggested that he hold back on adding oil for a while at least till it got down to 5.75 qts. Guess what. It never went below 6.5.
As some engines get older there is an increase in crank case pressure and then a increase in blow by that spits more oil out the breather.
Worn rings are a different thing. Consumption in the cylinders is something to always be concerned with.

[AlexPeterson]

Jeff, good point. I also wondered about the usage vs fillage, but haven't seen a correlation (I have inverted oil, so I almost never see any slop from the breather. I've let it go as low as 5 just to see the sub 6 quart consumption, but no change.

[Rupester]

Info above about fill level is dead-on accurate. Our flying club runs three 172's and the hard and fast rule is NEVER fill above the 6qt line. If you do, it just blows the "excess" all over the belly , making semi-annual cleanup all the messier. We've learned over a lot of hours over may years in several different 172's.

[asav8tor]

The following applies to using multi-grade oil not straight wt.

If there is nothing wrong with your engine and you very carefully track the oil level, you will find a significant relationship between hours on the oil and oil level.

After about 20 hours the much of the multi-additives that make the oil perform like 50wt are gone! Oil usage goes up. Adding make-up oil puts some back.

A guy that fills to 8 qts and keeps it there is doing the following:

( do not use a oil separator, not good for the engine )

(1) Blowing oil out the breather taking contaminates with it
(2) Constantly adding new oil replenishing lost additives


As you could imagine doing this would also influence the oil sample reading.

If you want to stay at 6qts to prevent breather loss, and you do not need to add make-up oil, change at 25 hrs to replace additives and remove contaminates.

If you stay at 8qts and at 25 hrs have added 5qts from breather losses, keep adding and go to 50 hrs before oil change.

[kcpgm]

I have 1550 hours on a h2ad in my -7 I bought the engine used from a cap 172

I Add 6 quarts at oil change it quickly goes to 5 qts on the stick it takes about 4 hours to go down a qt it will stay at 5qt for an other 20 hours then i add 1/2 to one qt by the time i get to 40 hours i change it and it is down to about 4.5qt on the stick

ken flying in maine

[asav8tor]

What oil are you using?

Originally Posted by kcpgm

I have 1550 hours on a h2ad in my -7 I bought the engine used from a cap 172

I Add 6 quarts at oil change it quickly goes to 5 qts on the stick it takes about 4 hours to go down a qt it will stay at 5qt for an other 20 hours then i add 1/2 to one qt by the time i get to 40 hours i change it and it is down to about 4.5qt on the stick

ken flying in maine

[kcpgm]

if you asking me it is aero shell 15-50 it has the additive in it that is needed for the H2AD motor

ken in maine