Oil Consumption Increas[ing] ?

humptybump · #1 09-30-2014, 08:57 AM

I could use a little "Engine 101" education.

How does the engine use "up" oil ?

Background:

My engine really does not use much oil - when I say "much" I mean a little more than a quart in 50 hours.

I don't over-fill at oil changes. I put in 6 qts and then fly about 5 hours before adding 1qt. Then I end up at about 5.5 qts by the time I'm at 50 hours and ready for the next oil change. I have a small mat under the airplane and it rarely gets a drip (perhaps a teaspoon over the 2 years).

The engine has about 350 hours on it now.

This time around, I'm 34 hours since my last oil change and I've added about 1.5 quarts. I'm not panicking. I'm just trying to get educated.

Mike H · #2 09-30-2014, 09:43 AM

Engines "use" oil by either burning it or by blowing it out of the breather.

You have an exceptionally low oil usage rate and should be verry happy. The max limit allowed by Lycoming is somewhere near a half a quart an hour. Most people are happy with using a quart in every five or six hours. If it were me, I would not be concearned. Oil consumption will increase with increased engine time and normal cylinder/piston/ring wear.

http://www.lycoming.com/Portals/0/te...onsumption.pdf

humptybump · #3 09-30-2014, 09:45 AM

Thanks Mike. I know I have very low oil consumption (and happily so). I know so little about what is really going on in the engine, I decided to ask for a little education :-)

Thanks for the link!

Mike H · #4 09-30-2014, 10:09 AM

If you see a sudden increase in consumption you may want to perform a compression check to see if you have a cylinder issue such as a broken ring, scored or worn piston/cylinder....

phil_101_99 · #5 09-30-2014, 10:16 AM

My O-320 also has low oil consumption 380 hours I have only add 2 quarts and the second was just last week. Normally I do oil changes at 40 to 45 hours .

Phil

bkthomps · #6 09-30-2014, 10:27 AM

i'm investigating this too, i've been told to verify the prop shaft seal. if it gets a tear or leak, it can expose the crankcase to upper deck pressure and lead to oil going overboard

this is on a continental, but maybe lycoming has the same

humptybump · #7 09-30-2014, 10:34 AM

Quote:

Originally Posted by Mike H

If you see a sudden increase in consumption you may want to perform a compression check

That will be easy. The plane just went into my shop for it's condition inspection !

Bavafa · #8 09-30-2014, 11:24 AM

I have heard that too little oil burn is not as good either. I am not sure how little is too little or what I have heard has any merits so....

BillFear · #9 09-30-2014, 11:44 AM

We just found a pretty substantial leak in our Saf-air quick oil drain. Only happens when engine is running at higher RPM and it only recently became obvious on belly just behind cowl hinge line. never had any oil on inside of cowling. We were up to using a quart every 2-3 hours.

Saf-air sent new O-rings to rebuild the oil drain, hoping for the best with this simple fix.

N520TX · #10 09-30-2014, 11:52 AM

Quote:

Originally Posted by BillFear

We just found a pretty substantial leak in our Saf-air quick oil drain. Only happens when engine is running at higher RPM and it only recently became obvious on belly just behind cowl hinge line. never had any oil on inside of cowling. We were up to using a quart every 2-3 hours.

Saf-air sent new O-rings to rebuild the oil drain, hoping for the best with this simple fix.

How did you diagnose the problem to the oil quick drain? I've been chasing a pesky leak for a while now, with the same symptoms you describe -- on the belly behind the hinge with none on the inside cowl .. not 2-3 hrs per qt tho, yet.

--Ron