I use tx7 in my gear box, powersteering, and engine, but I refuse to put anything other than castrol mercon v in my transmission. I've back flushed my trans properly with an rti trans fluid machine at my work but I always supply my own fluid. I do the complete flush usually 20qts through every 30,000miles. Between every 100% fluid flush I change my filters, in-line aftermarket and the one inside the trans. I use only motorcraft trans filters. The only trans problem I've ever had was a day where it neutraled out twice, each time while making a hard turn. The problem was remedied by topping off the fluid, 3/4 quart low, and changing the extension housing seal and dipstick tube o-ring. Now that it doesn't leak I never have to top it off and it's never mis-shifted since.