[Cobra R...anger]

i know that ford says to run atf in t5's, but i have been told that i can run redline synthetic mtl. and it will be fine and make shifting smoother... is any of this true? i was under the impression that the atf was needed because it was a lighter weight oil in order to properly lube the bearings. so in short is anyone using redline synthetic mtl.. or have any reasons why or why not to use it? thanks very much, Jason