Heat is what destroys many transmissions. The heavy load you pull or push will cause the transmission temperature to rise, sometimes higher than tolerable. Installing a high quality auxiliary transmission cooler will benefit the transmission and extend its life in service. Most importantly, if your vehicle is equipped with a "Tow Mode" button, use it. Also, if you are towing in OD (overdrive) and the transmission starts constantly shifting to maintain speed it will become hot, so downshift to D (drive) or press the OD (overdrive) cancel button. When plowing snow, make frequent stops with the transmission in idle; this will help keep it cool. And remember, come to a complete stop when shifting from forward/reverse!