I had the transmission fluid changed on my '99 150 FS at a quick change place and they used the machine to flush the system. Before they started the flush the guy added a cleaner additive and let it run for about 10 or 15 minutes, then started the flush.

I want to change the fluid on my '98 Expy and '01 Screw myself. I'll drain the TQ plus drop the pan. Are you guys adding a cleaner additive or just changing the fluid. I've heard it is better to change the fluid while it is still hot because it removes more contaminants, true?

 

It is better to drain it when it's warm.

For another way to do it, see this article:
http://www.ford-trucks.com/articles/...hangingatf.php

I don't use any additives.

 

If it ain't tranny fluid I wouldn't poor it in. Just use top quality fluid and change the filter.