In article , "Dennis O'Connor"
wrote:

Well, there's preheats and there's preheats...
A quick preheat with a red dragon makes you feel warm all over (so does
urinary incontinence while wearing a dark wool suit) but doesn't do much
of
anything except make the exterior sheet metal, fins, etc., temporarily
warm... The oil is still at ambient in the pan, and definitely ambient
upon
entering the oil pump... And that great steel slab of rotating oil
passages
they call a crank is still at -4 degrees, or whatever, to the oil trying
to
flow through it - chilling the 'supposedly' warm oil quite nicely and
instantly...
notice that the crank has two or more 'ambient temperature equalizing
heat
sinks' firmly attached......
Of course, you feel all warm and secure - if not actually doing a lot for
the engine - so I suppose that's worth something...

well, I've done the no-preheat thing on a 30 degree day and the prop
didn't spin all that fast (barely started). With a preheat on a
20 degree day the prop spins a lot faster. Preheating does something
for my engine.

--
Bob Noel