Michael wrote:
There is another [simple] way to seal-up lead fouled valve seat: do a valve lap without pulling the jug as Paul New describes in this article. I have used this technique with excellent results. TAS valve lappingThat said, the OP is concerned about rings – not valves.
Understand but in the interest of putting forth information I mentioned that in trying to free a sticking oil ring it actually also helped with low compression due to a leaky exhaust valve.
If humans didnt share information we would still be up in the trees. Although I see that information can be misconstrued, misinterpreted, misunderstood and so that is why the human race created the lawyer and judges. 
Peter wrote:
I don’t have bunged-up or leaky valves. Borescope showed them to be perfect, compression is good too. 75/80 mostly.Would I be right in that if the front crankshaft seal was leaking, there would be visible oil inside the bottom cowling?
Can a blown crank shaft seal pressurize but not leak oil?
C210_Flyer wrote:
If humans didnt share information we would still be up in the trees.
That’s why I shared the valve-lapping trick !
Can a blown crank shaft seal pressurize but not leak oil?
I think the way it is supposed to happen is that if the breather pipe gets clogged up, and you have a lot of piston ring leakage (there is always a lot else our oil would not come out so filthy) then it has to come out somewhere, and it’s going to push out past the crankshaft seal.
Im not sure you have that anyway as Ive said before. But just an academic discussion.
If for whatever reason the breather gets plugged. Could it be due to ice very low power, high altitude, and low temperatures? If the plugging was temporary and it causes the seal to break would you have oil coming out the seal as the case is pressurized or just the breather or both?
I’ve just done a 2.5hr flight today, to FL100, and the oil usage seems to be 1qt in 3hrs.
I won’t know for sure till I get a chance to check the dipstick with the engine stabilised (tomorrow onwards).
It’s plausible that it’s been like that, or approaching that, for about a year. So I think this is OK to fly with.
I always have that oil consumption … only right after the oil change it’s a little less. And all my spark plugs are nice and dry and I think nothing is wrong … I think you should be ok.
It sounds extremely high to me. Have never seen more than 1 l in 10 hrs. On my trip to Norway past summer I flew in excess of 20 hrs and did not even add oil. It was 7 qt when I left and still above 6 qt upon my return. IO360 A1B1 (?)
a climb to FL 200 or more requires a lot of time at high power settings and I ´d say you will see a lot higher oil consumption than doing a 5 hours cruise at say 60 % power. Maybe you were only confused from a flight including a long climb as compared to the usual low level hops . So really there may not be much wrong with your engine apart from possibly slowly increasing clearance of piston rings in their grooves heightwise, meaning axial play. That increases oil consumption due to a pumping action of rings with time and many hours of operation.
VicI wish I had been collecting the data more carefully in the past.
My long term oil loss is probably about 1 in 5.
As I mentioned before, it’s easy to lose track of it especially if doing a series of short (say 1hr) flights because even with 1 in 3 the dipstick level drops only 4mm after each of these and only Sherlock Holmes is going to notice that on the preflight. And when it gets a bit low, you just throw in another bottle.
The only historical record I have is the total number of fills between services but that can be distorted by the fact that one lets it run down towards a service.
a climb to FL 200 or more requires a lot of time at high power settings
The climb is about 0.7-1hr and the power level on it is quite low, not high (I am non-turbo). I think very low power (say 30%, FL210) buggers up the engine with some muck on the rings.
