tranny, transfercase, rearend oils??

I have a florida truck, now in Canada with a cold snap of -40.
Truck won't shift into gear without shutting off the engine first then putting into gear before starting again. Naturally, the oil must be too thick. Should i change the transfer case, tranny and rearend to the same product Mobil 1?? Is it easy to do? seems the new generation truck needs special tools to complete, is it the same for the 1st generation?
Thanks

 

these are easy changes man. mobil1 will be great....its what im running in my 04. for the rear....you'll need a ratchet and a 24mm socket for the rear diff and for the transfer case......and you will need a big hex head for the front diff. also........get a bottle pump(one like you would use on a boats lower unit)....this will aid you in filling the diffs and transfer case greatly. mobil1 75w90 all the way around is what i did, and 4x4shifts alot smoother and quicker now.