I just read the 65 degree comment, and from somebody else's post had Texas
stuck in my mind.

I have a milkhouse heater with an aluminum dryer vent hose.
It's bungeed to a small step ladder. I plug it in, and stick the hose into my
oil access door and walk out. It's been running all winter like that. I set the thermostat to trip somewhere between 30-40F in the hangar. This results
is a warm to the touch, but not hot engine all winter.

When the weather is typically above freezing (say 40+) I don't preheat. I
run 15W50 Aeroshell, and while it cranks a bit slow in cold(er) weather it
starts up, and I give it a decent warm up at idle before taxi.

Below freezing my engine (IO-240B) is pretty much impossible to start
without preheat.

Regards,
Jeff