In Reply to: Magnetic oil/block heater posted by dave#1 on October 08, 2018 at 11:42:08:
Look at the oil pan. Make sure there's a flat spot the right size. If the oil pan is stamped steel, you risk some cooking of the oil right next to the heater. The N-tractors have a cast iron oil pan with ribs on the bottom. I've been sticking my magnetic heater on the flat side of the pan, as close to the bottom as I can get. A cast iron oil pan is enough of a heat sink the heater is not going to burn the oil, even if left on for several hours.
This is central Virginia. We get some single digit overnight temps and an occasional dip below zero is not unheard of. Most of the time I stay in the shop near the wood stove and wait for it to warm up a bit before venturing out. If I need a tractor to plow snow or haul wood, I go out and put the magnetic heater on it for 30-60 minutes. The tractor certainly seems to crank faster with a little heat in the oil.