[gazelleintense]

This truck has 60,500 miles on it and this has the original trans fluid in it. Seems to be working fine.

I hear two stories about changing trans fluid. One says you should change the filter too, one says flush only is fine.

Which is true?

[TxGreaseMonkey]

You want to drop and clean the pan, change the filter, and refill with Mercon V ATF every 30,000 miles. This is the procedure Ford recommends. If you don't drop the pan and change the filter, T-Tech type machines will stir up the crud in the bottom of the pan, clog the filter, and your transmission will shortly fail. It's amazing how much crud forms on the bottom of the pan every 30,000 miles. The local Ford dealer told me, several years ago, he gets a lot of transmission rebuilding business from people who didn't replace the filter and only used the T-Tech machine. Install a B&M drain plug in the pan and make life easier in the future. It will encourage you to change it frequently.

With 60,500 miles, your eyes will likely pop out at the crud from the clutch packs in the pan. I recommend using Mobil 1 Multi-Vehicle Synthetic ATF or Amsoil Universal Synthetic ATF. It's a simple job to do it right and it will make a huge difference in how long the ATX lasts and how well it performs.

The best of both worlds would be to drop and clean the pan, replace the filter, and change the fluid with a T-Tech machine. This way, the fluid in the torque converter and transmission cooler gets changed, as well. This can still be accomplished, on your own, without the fancy equipment.