I had a '96 Windstar with the AX4S transmission.
The Windstar had more issues with the transmission due to the extra weight of the vehicle.
The ATF fluid change interval, as per the owner's manual, was every 30K miles (21K miles for severe service).
I highly recommend regulare ATF fluid exchanges using a high quality synthetic fluid that meets the Mercon V specification.
Mobil 1 ATF is a good over the counter product.
I used Red Line D4 ATF, which is also very good.
I don't think that there is a drain plug on the pan.
My '96 Windstar did not have one.
A auxillary cooler is a GREAT addition.
Another thing that I do.....in stop and go traffic, particularly in hot weather, I set the climate controls to a setting that has the A/C running.
THIS keeps the radiator fans running when you are not moving more than a certain speed.
This is critical because this keeps your transmission fluid MUCH cooler, as stop and go traffic is when you will really heat up the transmission.
The Auxillary cooler will also GREATLY help in this situation as well.
If you want to further help your transmission last.....add a Magnefine filter to the fluid return line (going INTO the transmission).
The BEST of the in-pan transmission fluid filters will filter down to a nominal particle size of about 80 microns.
The Magnefine filter will filter down to a nominal particle size of about 35 microns.
This will help to keep the critical fluid valve areas clean.
A Magnefine is very inexpensive and easy to install/change.
Recommended Change interval is 15K miles or once a year.
Inside the Magnefine filter.....filter element with a pressure bypass to let fluid flow through the middle of the element if the element should become clogged.
The BIG washer looking item is the magnet that catches a lot of ferris particles since all the fluid flows over it.
