I leave mine on all the time when the temperature is close to freezing.
That is most of the winter.Before that, I make a trip a day or two prior
to plug them in. Over ten years, no problems.

Down the row the guy plugs in after every flight, always on. Most of the
year. All but for the middle of summer. Ten plus years, no problems.

John

cpw wrote:

I live in northern lower Michigan where we have real winters some years
(not this one yet). My partner and I own a 2000 Cessna 182. We are
currently debating the proper use of the Tanis engine heater. It has
been our practice in the past to plug the heater in after a flight and
leave it plugged in until the next. We have heard lately that best
practice is to only use the heater for a few hours prior to flight.
Any opinions among other owners in cold climes?
Thanks. CPW