The best way to use an engine preheat system is to plug it in 10 to 12 hours before a flight. But driving to the airport to plug in the preheater costs time and money. Some pilots avoid that by letting the preheater run continuously between flights, but this wastes electricity ($20 to $70 per month depending on the system).
It also quickly pays for itself, at a price far less than other options —only $189, or $89 if purchased with a preheat system priced over $400, according to company officials.
For more information: ReiffPreheat.com