Tow Haul Mode

Using Tow/Haul is not going to affect fuel economy while towing and you are definitely not going to go wrong using it for all your towing. However, with a new F350 diesel towing a lighter tag trailer, something under 8k lbs, tow haul is hardly needed. If you find it more comfortable to tow light trailers set to "normal" I'd recommend using "normal" for towing.  Activating the Exhaust brake affects the shift points to some degree as well. Sometimes with a light trailers I'll use "normal" and no exhaust brake, sometimes "normal" plus EB. With a heavy trailer I usually use Tow/Haul with the EB set to "auto". If just driving on flat ground at slow speeds I will sometimes set the truck to normal no EB even with a moderately heavy trailer, (I consider my fiver a moderately heavy trailer at about 16000 lbs).