I bought a 96 Mystique (V6) with about 75k miles about 2 months ago. The ATF looked pretty good. Since then I've done a 2 drains and refills (I know you only get about 1/3 of the fluid by pulling the drain plug.) On the first one I refilled with Valvoline Maxlife and the second I used 2 qts Mobile 1 and the rest more Maxlife. The transmission works fine and works smoother after the fluid changes. In the spring I was planning to a full fluid replacement. (I'm thinking of “cheating” by cutting the return line and using a male-to-male hose coupler, because getting to the end fittings is a pain.) I'll probably put in Mobile 1 at that time. Normally, I would also add a transmission cooler, but again, space is very tight and I haven't see a good place to mount it. Also, when it's cold it takes a while for the ATF to come up to full temp (and go into OD), so I'm not sure it really needs one.
My question is if there is anything else I should be doing like adding an additive (Lubegard, or one sold by Ford). I would much prefer to do extra maintenance on the trans rather than have to get it repaired.
