Great questions.
I usually fill to 7.5. It is hard to say on first hour because of the durations of flights recently. The plane has a fresh oil change. It was happening pre oil change recently, it is just all my flights were shorter in duration, so wasn't as bad. Average appears to be 1/4 qt per hour. I'm positive it is coming from the breather because the extreme cleanliness of everything else around the breather and the oil dripping directly from inside the breather post flight.
Here are my last flights since oil change in order:
1. 4 hrs, start 8 qt, finish 6.5 qt
2. 3.8 hrs, start 7 qt, finish 6.5 qt
3. 2 hrs, start 7qt, finish 6.5
4. 4 hrs, start 7.5, finish 7.25
5. 3.4 hrs, star 7.25, haven't checked finish yet but still visible oil on belly
At the end of every flight I had visible oil on the belly of the aircraft. The oil is still fresh and clean even though it has been 17.5 hrs since oil change. Oil is AS 15w50 with camguard
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