If you flush just remember to shift the gears around. If your car has never had the ATX oil changed then there might be problems. The worn metal flakes inside the tranny can come loose and float around into bad spots. So a flush might not be a good idea. Just like the lady at work that gave her 96 Honda a flush and an engine light came on 2 days later. There was a problem with a switch inside the tranny. I just cleared the code and it never came back. So while this problem was just a glitch for her, you can see that there are things going on inside an old ATX that should be taken lightly.
You can have superlube do a gear box flush.
What I would do is while the car is cold drain the fluid from under the tranny. Make note of whatever amount comes out and put the same back in.
If you want, you can try adding a bottle of lucas transmission fix.
