Oil Consumption

[Luvjet]

17.5 hours to Oshkosh and back.One quart every three hours. This just doesn't seem right. I understand that it is "within limits" , but still........ The engine has only 75 hours on it since complete overhaul. Even the propeller was o'hauled though it had no problems. Yes, it has chrome cylinders. I ran it at low altitude 2650 rpm's full rich at 1500 msl for 25 hours. It was borescoped at 15 hours with the results showing a beautuful break-in. No oil on the belly, no oil on the floor, no dirty spark plugs.Runs strong and as smooth as the 0-300 reputation is for that. Any body out there have input as to the high,at least I think high, oil burn? On another note, I can't believe the 170 parking filled up so fast! I got there Thursday and they said the 170 parking had been full since Sunday afternoon! Walked through the 170's but most of you were out and about. Oh well, next year.

[Luvjet]

That seems more realistic Arayana. Were you doing anything out of the ordinary when you burned 3.2?

[FredMa]

Does your compression check normal and consistent between cylinders? If there is nothing abnormal mechanically my guess is that you might be overservicing the oil. Perhaps your engine got a new dipstick (possibly the wrong part) installed at overhaul.

[GAHorn]

FredMa has a valid point. My own oil consumption was about 5 hrs/quart until I quit trying to keep it above 6 qts. Then the consumption dropped to 10-12 hrs per qt.

The correct dipstick is important also. A 172 dipstick in a 170 will underservice it, however (and possibly lead to increased engine wear and higher oil temps)...not overservice it.

[DWood]

Luvjet:
I have around 300 SMOH on mine and if I fill up the oil, it will blow out the first couple of quarts and then stabalize between 5 to 6 on the dip stick. I broke mine (chrome cylinders) in with mineral oil and then switched to 100W Aeroshell (80W in winter). Local flights I leave between 5 and 5.5 on the dip stick and put it up to 6 for distance. There is actually more in the engine. Next oil change you might drop in 6 quarts and check the dip stick.
You might search for previous posts on oil consumption as this has been discussed indepth.
Dan

[russfarris]

Channel-chromed cylinders do have higher oil consumption than steel. When I had channel-chromed on my 170B, oil consumption was exactly in the range you experience, with no other indications like fouled plugs, ect. of a problem.

Russ Farris

[FredMa]

If you have compressions that aren't consistent with other cylinders or an engine with only 75 hours you might also consider the possibility of piston ring gaps not being staggered correctly. I would consider all other possibilities first though.

[Luvjet]

Thank all of you for the great response. I will keep the oil at no more than 6 qts. and see how that works. The dipstick (besides me) is normal. It is original.

[170C]

The comments regarding keeping the oil level at 6 qts is interesting. I, too, have found putting 8 qts in my O-300B results in at least the first qt ending up on the belly or elsewhere so I never put in more than 7 qts and that includes having put on a new filter. I have something over 800 smoh and likely have the C-172 dipstick (since it is a 172, but has the tailwheel conversion). I have marked my dipstick so I know when I have 7 qts installed. I flew 25.8 hrs on the convention trip to SD. I added one qt upon arrival in SD and put in another in either Tucson or Deming. When I got home I still had 6 3/4 qts showing on the dipstick and after it sat for a couple of days there was a tablespoon or more of oil in the drippan under the engine so I know some went on the belly as well. I have about 3 pushrod rubbers that leak! If my math is correct I am only using about 1 qt to 13 hrs on steel ECI cylinders. I think my oil consumption may be a bit higher on short trips, but not sure. The SD convention trip was flown at anywhere between 2500 - 2650 rpms. I mention the above just as a comparison. I may give the 6 qt level a try to see if it changes anything on local or relatively short trips and use the 7 qt for long ones.

[Bruce Fenstermacher]

and after it sat for a couple of days there was a tablespoon or more of oil in the drippan under the engine ........... I have about 3 pushrod rubbers that leak! ............ I am only using about 1 qt to 13 hrs on steel ECI cylinders.

Frank lets get one thing straight. YOU DO NOT HAVE AN OIL LEAK. Those pushrod tube rubbers may be shiny from a slight fog off oil that is barely escaping which hardly classifies it even as a seep. But it is definitely NOT a LEAK.

A real oil leak is when you add a quart every 3-4 hours to bring it up to 6 quarts from 5 and there is a tablespoon of oil dripping on the floor from the tail wheel.

[bagarre]

My O-300D has 700 hours smoh and will burn a quart an hour if I insist on keeping it at 8 quarts.
If I let it settle down, it stays at 6.5 quarts and burns a quart every 10 or so hours.
For some reason, these engines just don't lie to be topped off.
I had an old Jeep like that. You could add oil every day if you wanted it full. Or, run a quart low and it was happy as a clam.
Never figured out why but it never hurt the motor.

</$0.02>

[170C]

Bruce, funny you should mention the oil dripping off the tail wheel. I put air in the tires on my tug yesterday and while doing so I noticed a few drops of oil on the hangar floor. Sure enough, it had dripped off the tail wheel spring One thing about it, those springs won't rust up as long as I have that oil "mist"