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From: N295VV@aol.com   (n295 v v @aol.com)

After hearing of the cylinder problem experienced by Carl LaRue, I am
repeating my thread on engine leaning:

Neal Pobanz,  recognized world-wide by Bonanza owners as a Guru, gave me the
following advice on the TSIO-550 engine:  "You can lean this engine and buy
cylinders at 700 hours, or you can not lean it and buy gasoline--your choice"

 Since Neal had been interrupted about four times during our conversation with
telephone calls from all over the world, I figured he was an authority of some
note, and I decided at that time to follow his advice.

He now has a group of people getting 1800-2100 hours on their engines.  While
this is not scientifically significant, any anecdotal documentation should be
taken seriously, since Continental is known for cylinder overhaul need at low
hours.

And, yes, I have received the usual criticism regarding this.  But my
cylinders are 325 degrees average from 200kts to 260 kts.   Additionally, the
effects of shock-cooling are lessened, since there is a constant flow of extra
cooling gas in the cylinders, which are cooler to start with.

And when I don't lean, the extra fuel is converted to extra speed, which I
want.  I fly at 85% power all the time anyway, so the extra fuel cost is only
noticable at low speed such as landing and taking off.

A caveat however--I change oil and filter every 25 hours, and I open my oil
dipstick after every flight to let the volatiles boil off from the hot oil.  I
use aeroshell 15W50.

David Jones