what do you think is the probability that the synthetic, detergent oil cleaned everything up and fixed the issue?
100%.
This is a known process. You just aren’t going to read about it in a Lycoming flyer 
Trying to derive any hard data for oil consumption from such minute increments on the oil dipstick and such short flights is just about worthless, IMHO.
Except I have not been doing it that way. I have been far more careful with procedures. For example one needs to wait till the next day before checking the oil level. That Coventry flight was done a week ago and I checked the oil yesterday.
Peter wrote:
Except I have not been doing it that way. I have been far more careful with procedures. For example one needs to wait till the next day before checking the oil level. That Coventry flight was done a week ago and I checked the oil yesterday.
And what about the randomness of the oil filter & cooler (and ALL the other nooks & crannies) emptying or not ?
Michael wrote:
or example one needs to wait till the next day before checking the oil level. That Coventry flight was done a week ago and I checked the oil yesterday.
So you always wait exactly 6 days before checking ?
edited for precision
And what about the randomness of the oil filter & cooler (and ALL the other nooks & crannies) emptying or not ?
I was always careful after any oil change to run the engine and exercise the governor, so the governor and prop hub and oil filter get refilled 
So you always wait exactly 6 days before checking ?
No; tests showed that after about 5hrs the “gain” in oil level is less than 1mm. After only 1hr the oil level is understated by about 3mm. So overnight is good.
And one has to make sure the nose oleo is equally compressed (engine angle).
In the end, it is never done on just one flight. The proof is how much oil you have to add in the longer run, and there the results are obvious.
Is one of the takeaways from this to add 1/2 qt of Mobil1 0W20 a few hrs before an oil change as “preventive maintenance” or should that be reserved as a “last resort” for when things go wrong?
I am tempted to, in the future, add a quart of 0W20 after a long high altitude (FL200 or so) flight… but I can’t see any need to do this regularly.
Peter wrote:
In the end, it is never done on just one flight. The proof is how much oil you have to add in the longer run, and there the results are obvious.
What I said …
BTW: Where did this Mobil 1 0W20 stuff come from ?
Not going to say.
Peter wrote:
Not going to say.
Top Secret ?
While you’re at it, you might try MMO, it’s been credited with curing all sorts of engine problems as well !
