On Fri, 21 Jul 2006 17:12:41 -0400, "Morgans"
wrote:


"Dick" wrote in message
news:rqawg.1329$K94.452@trnddc01...
Having always changed the aeroshell 100 sae50 change in my c85 every 25
hours, I'm considering extending the aeroshell duration to maybe 35 hours.

My flights are in Florida and usually around an hour (or sometimes two)
and
am currently burning/losing up to 1/2 quart per hour when filled to 3-1/4
quart line on the dipstick.

Of course I'm thinking about oil cost and feel like adding that oil each
flight hour does help it's cleanliness and service life.

Not as much as you would think, according to studies I have read.

The problem of "changing oil by adding lots more" is that the PH is screwed
up in what is left, and if you don't get rid of the oil that is too acid,
all it does is instantly change the oil you put in. Not to mention the bits
of metal and carbon, and other crap left in there.

If you think the engine is about shot, perhaps you go ahead and do it. Who
knows, though. You may do the last little bit of damage to the crank or cam
or a jug, to take it out of reparable tolerance. That would suck.

Dick 3 1/2 quarts on the dipstick seems sus to me but I dont know what
the dipstick range is on the c85. on my O-200 I have ended a long
flight with that oil level and the engine rattled away quite
alarmingly. I fly with the oil up at 6 quarts and the engine is much
quieter(one of those quarts is in the oil radiator).
Short flights that dont boil off the moisture are supposedly the
killer. long flights will keep the oil free of water.
I've flown the oil for an entire year (75 hours) and it still came out
decidedly new looking. Australia mandates oil changes every 6 months.
....but then they mandate lots of other things that seem as silly.
If you want a long life out of your engine it needs to run like a
taxi. ie all day every day.
Stealth Pilot