I'll agree with Mobiltech, the espars are the way to go, they'll cut in at I believe 70 deg F and out at about 170, just before the thermostat opens, keeping the engine at optimum temp. They are programmable, will come on 2 hrs before anticipated start time, yet 45 minutes are all they really need for starting at -30 deg F. Old school hooking up hot pickup engines to -30 engines was done for years, and it cracked heads for years too, a 200+ degree change in seconds was too much to take for a lot of heads. They can be bought for about $1000 here in Canada, and are easy to install, they have they're own water pump, so no worries about convection circulation of water. They're simple to operate and troubleshoot, I'm thinking if you can figure out how to post on this forum, you can set them and retrieve codes.