yes a t-tech is one of the only ways to get all the fluid out.but first ya gotta look at how many miles are on the tranny.and when it was last serviced.i have the t-tech machine at my shop but i will NEVER flush one out over 150k.
when it gets to that point if its not regulary maintained its wise to just drop the pan and change the filter and clean all the junk out of the bottom and magnet. if ya got more miles then that i would just suggest draining and refilling only whats in the pan. believe it or not but ya can kind of send the tranny in shock and it will fail.
