I usually plug in my vehicles if it gets to -15C or colder.

We often see temperatures of -30C or colder during the winter a block heater is a must if you plan on your engine lasting in our climate.

 

10-15 minutes is pretty excessive, the best way to warm up the engine is to start it, let the idle drop, then start driving it slowly keeping the rpms low until the engine reaches operating temperature. This is especially important on automatic vehicles since the transmission fluid wont warm to operating temperatures without driving the Jeep.

 

I pretty much only plug mine in below probably -20ºC. Even then, only if I'm going to be parked outside for more than four hours and a plug is conveniently located. Definitely need it on the -35ºC nights.

Edit: I almost never let it idle after starting. I just swish the manual tranny through the gears once or twice then start moving like normal.

 

I also ordered one for my 2012 sport becuase I plan to eventually drive to the northern part of alaska on a trip

 

I have one on my 2012 and I don't plan to use it much because it's parked in a heated garagemost of the time, but for $35 if I need it once when I have it parked outside sometime on a trip it will be money well spent! Much easier on the engine at start up!

 

my dealer was thinking they came on the rubicon, i was asking him friday about putting one on the 12 rubi i just ordered, he said he couldn't find the option to have it ordered...so he figured it just came on it?? can anyone confirm how to tell? thx

 

Do you know the wattage? I'm looking at the 250 watt heater, rated for engines with 4.5 to 12 litres of oil. This should be safe for the 3.8. The next smaller heater is 125 watts, seems a little small for what it needs to do. I plug in at -15 deg C. A few minutes warm up is good until around -25 deg C. Colder than that and I give my vehicles closer to 10 minutes. At -40 I used to let my 87 Comanche run with the t-case in neutral and the manual trans in 1st gear. That was needed to get it moving without stalling it. -40 is just bad news, no fun is to be had. Heated seats rock by the way