i put a quart of atf in every tank and have been for 150k miles now. and yes ulsd is junk. truck still runs like new. now i don't know whats different in the powerstrokes that it is so bad for it. my dad also adds atf in every tank on his 6.0 we only put powerservice in every 6 fill ups or so to keep everything clean. i don't like to use it alot because it has alcohol in it and i hear thats bad for the motor.