From memory my 2012 6.7 recommended varying the speed for 500 miles and no towing for 1000 miles, but read the man to get the current recommendation. It could be that only 3% of the trucks made need a proper break-in--do you want your truck to be in that 3% and have problems--just follow the guidance. Be VERY careful about fuel (to the extent that you can) because ethanol, gasoline, or water in the fuel will blow up the hp pump and ruin the injectors. MANY people have no problems with their fuel systems, however, why test the odds. The Motorcraft fuel treatment adds lubricity to help protect the pump, as well as de-mulsifying water so the filter can catch it. Dieselstop.com is a good web site for Ford owners.