I used to live in Amarillo, Texas. I used to have a 1984 F-250, 6.9 liter International Diesel. Man out in the open plains there you'd better have a block heater for your engine. I left my truck out in a parking lot where I worked without the heating block plugged up all day. That truck didn't crank for 2 weeks setting out in 15 degree weather. As long as I kept it plugged up, I had no problems. Cranked up better than a gas engine on freezing days. Now down here in Austin, that's a whole different story. I feel for you guys in the North.