thanks it was the first thought that popped into my head after i read that article.
i know on our powerstroke f250 they told us to change it every 30k mi just for everyday driving no heavy towing. but that was probally to make sure it made it to the 100k mi warranty so they wouldnt have to swap it out.

but like mmelton005 said i to am a firm believer in changing fluids they do get old and dirty and dont perform as well as they do when they are new (just like everything else in this world) . so why not keep good fresh fluid in it so you dont burn the valve body or get sticking valves, poor shifting, or a fried torque converter from old worn out fluid with dirt in it and then a broke truck.