It was never not run for years at a time.. just a low overall usage pattern.

Michelle P wrote:

Paul,
I would consider the engine of $0 value in negotiating. That is an
average of less than 40 hours a year. Usage pattern is of concern as
well. If it sat for the last several years, very bad. If it was run
regularly to full operating temperature for the past few years, and
still runs good. this is better. Was the engine preserved when not run
for period of time?
Michelle

Paul Folbrecht wrote:

The 150 I had pre-buy'ed today has an O-200 with 940 SMOA but this
overhaul happened 24 years ago. Mechanic has pointed out that
Continental also specifies a time limit of 12 years on overhaul and
thus this engine is technically runout.

Do I have much cause for concern?? I know engines are quite regularly
run well beyond that time interval. After all, to make that 1800
hours in 12 years you have to fly 150 hours/year.

Compression is good (all in the 70s) but there is no oil analysis
available. Engine sounds just fine and also has good oil pressure.

I basically need to make a decision on this quickly and am stuck on
this issue. I am leaning heavily towards buying it. My mechanic has
said it is pretty unlikely that this time factor will result in
serious problems now, but that there's really just no way to tell
without an oil analysis or by watching oil consumption.