Engine preheater

Scott, I leave the cowling loose on the oil check side. Route a room heater with a piece of 6 inch flexible heat duct attached to it into the bottom of the engine. I have 2 blankets that I cover the cowling and all the air openings. I plug it into a timer that was about $20 at Amazon. Set it for 4 hours before flight. It starts and oil temperature is in normal range very shortly.

Good morning everyone. Does anyone have any experience with the use of preheater on a 415-C they can share?  Thank you.  Scott