Dave Stadt wrote:

How come the engine in my car with 190,000 miles is running fine with no
signs of undue wear with nary a single preheat.

Aircraft engines are usually designed to turn at about 2700 rpm max. Auto
engines are designed to turn about 5000 to 6000 rpm max. Since the valves are
closing much more rapidly on an auto engine, the springs must be made much
stiffer. Since these stiffer springs slam the valve head against its seat with
much more force, the valves are made much thicker to take the punsihment.

In short, the entire valve train of an aircraft engine is much more delicately
built than that of an auto engine. Skip the preheat, and you run a serious risk
of snapping a valve.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.