<<Again, from my chemistry background, if you want to speed up a chemical
process, just add heat.  In other words, if you want to make rust faster,
raise the temperature of the reactants.

So the bottom line is, in my opinion--water is always present,  and
extended heating causes more corrosion than it cures.  Use heating only for
a short period of time before and after the flight.

David Jones>>

You got it exactly right, David.  Just another data point from living in the
rust belt for many years:  If you want to rust your car out, drive it on the
wet, salted roads and then park it in your heated garage.  Unless you wash
off the salt and dry it out it is far better to leave it out in the cold -
colder the better.  When I had a jointly owned airplane in a hanger with
electricity there were partners that wanted to permanently heat the engine
in the winter.  I, being the "maintenance officer" steadfastly refused and
instead rigged a Salamander kerosene heater with a pipe to blow into the
engine compartment.  It would heat the cylinders of the engine in 15 minutes
(baggage loaded and preflight complete - except for draining the gas!) and
no corrosion in the engine.  Lots of frost and water droplets would show up
on the outside of the engine during pre-heat, but we were going to fly in a
few minutes, drying it all off.

Gary Casey