Hullheli, personally I would do the same with the Arf Version engines, all they do is install the same eingine that is purchased seperately, just for that peace of mind factor I would certainly clean it out. As far as the break in, set your high end needle to 3 1/2 turns out start it there, and try to get about a 1/2 gallon through at that setting, and then go to 3 1/4 turns and go through the other 1/2, after the 1st gallon I would go to 3 turns out, and run it there through another gallon, then adjust from there, the tt39 doesnt like too much past 2 3/4 turns out, you may be able to get to 2 1/2 depending on fuel used, and location. I would run a good fuel like Wildcat 20/18. As far as the weather I dont think it will care about the cold temps. Daz...