Excuse my ignorance, but how would valve guides, bad rings, etc cause it to
leak down to 5.5 quarts and then stop. It seems these causes would result in
a continued loss as long as the engine was run.

"Jim Macklin" wrote in message
news:kaStg.67770$ZW3.1299@dukeread04...
Do a differential compression test and pay attention to
valve guides play and seals, often the oil is not being
blown out the breather, but is leaking around the valves
[even one valve] and burning. If you have high leakage
during the differential compression test, you're getting too
much blow-by and that is raising the crankcase pressure and
blowing oil out the breather tube. If the breather is
blocked, it will blow the main seal and you'll see oil
behind the prop. If the oil level goes down fast and then
stabilizes, you may have a dipstick that is not calibrated
properly and you're over filling.

The engine is old, nearly ten years, check all the seals and
mating surfaces. You only have 900 hours, but that is less
than 100 hours a year. Corrosion in the cylinders and blow
by, and oil being sucked past the ring into the combustion
chamber are all possible, Check valve guides and seals,
differential compression and if available, borescope it.
Higher oil pressure would increase the leakage, but not
effect the valve guides or rings. An oil separator will
only help if the oil is going out the breather tube.


--
James H. Macklin
ATP,CFI,A&P



"Robert M. Gary" wrote in message
ups.com...
|I have an IO-360-A3B6 900 SFNEW in '97. I used to be able
to keep about
| 7 quarts in it without it blowing out. Now it seems to be
blowing oil
| down to about 5.5 quarts. Since I live in the 100F OATs
part of the
| country, the extra oil really helps cooling.
| Should I worry about what is causing the extra oil blow
out or just
| chock it up to an aging engine. I know some engines always
blow out to
| 6ish quarts.
| If I shouldn't worry about the extra blow out I'll just
put a separator
| on it, but I don't want to mask a problem first. One
recent change is
| we raised the oil pressure since the regulator had been
slipping prior
| to annual.
|
| -Robert
|