The o-360c1f in my 94 mxt, uses, or rather disposes of 1 quart every 4 hours. I have 450 hours on the overhauled engine, and it has used this amount since the beginning. Maule Flight rebuilt the engine so I have faith in the rebuild. I have had at least 6 A&E's look at it carefully and they can find no leaks, so it appears to just come out the vent tube. All compressions were excellent.

I found an obscure Lycoming service bulletin that had a formula for all of its engines and according to the calculation, 1 quart every 4 hours was perfectly acceptable, so I quit worrying.

Also, Lycoming says the O-360 will run all day long on 4 quarts. I don't do that, but it is comforting to know it.

gregorydshanks wrote:1 quart every 4 hours

That sounds like a messy belly!

I have about 18 hrs on the recently overhauled io 360. 900 hrs on the McCauley. Yesterday I noticed a few fine streaks of oil on my freshly cleaned windshield. I had a good 10 quarts of oil in it. Maybe I overfilled it? Anyone seen that before?

O-360-C1F takes a maximum of 8 qts on the dipstick but I usually never fill more than 6.5 for normal flying or 7 for extended trip. Otherwise, it blows it out the breather tube onto the belly.

According to the Textron Lycoming Operator's Manual that I have, the oil sump capacity for all O/IO-360 engines except the AIO-360 is 8 qts.

a "few streaks on the windshield" is seldom from the engine but instead from the prop.

I also have a Continental IO360. I keep mine at 10 quarts which is correct and I agree that a few streaks more likely come from the prop.