On Fri, 14 Nov 2008 13:48:49 -0500, "Roger Long"
wrote:

The mixture is adjusted constantly on general aviation
engines and the engine manufacturers were still giving the advice that put
the most stress on the engines, minimized their life, and fouled up the
cylinders the most with ash. Why? Because running the engines the way that
was best for the individual owner meant that everything about the engine had
to be nearly perfect. ...

It's interesting to notice how much LONGER auto engines seem to be
lasting these days. This is not just that a made in Japan or Korea
engine is somehow better - but rather that all engines have engine
controllers any more, with port fuel injection as likely as not, and
adjust themselves on the run, to stay optimally lean and correctly
timed.
So they stay clean, and listen for ping, and sniff for stochiometry,
sometimes with two O2 sensors.
Too few aero recips are doing that. Porshe's try fizzled for instance.
The market is small.

BrianW