I used AMSOIL MTG and it shifts great when it warms up, or the temp is over 70. Still shifts like **** in cold weather (below 50) until it warms up though.
BTW ... prepare to get flamed, there is a small group of Ford apologists out there that insist that there is nothing wrong with the MT82 and that it's all due to driver error.
There are a few TSBs on the MT82 as well, might want to look them up and take the car to the dealer first if you care about your warranty.
Pages 73 and 74 of this will help bring you up to speed...