Preheat

Winter is comming to Ohio ( thou the 60 deg day today disagrees) and the
subject of engine preheat arrises. I have a Tannis for the cylinders and a pad
to heat the oil. I can call the FBO and have them plug it in an hour before I
arrive and the engine is, at least, not cold to the touch. Still there is the
time when I fly somewhere for dinner or overnight and park in the cold, cold
outside.

The question, why is preheat necessary?

If it is OK to start the engine cold when the temp is 60deg F and let the cyl
head temp go up to 500 or 600 deg, why is preheat recommended when the cold
temp is 10 or 20 deg? The percentage difference in the delta T is less than
10%. Are the engine parts that critical that this small percentage change
makes that difference?

I use 15/50 oil so the "cold" oil should be a good at the lower temp.

Chuck