It would also depend on your usage. "General" use vehicles can use anything meeting the spec., but if you want to keep the car for a long time and you operate under extreme conditions (-40 temperatures or lots of towing near or over the rating) you might want to go with something designed for your specific needs. I switched to Dexron VI because it was partly engineered by Petro Canada for extreme cold protection, but now they have the MV fluid out that meets Mercon V specs and is
also designed for cold temperatures, so I'm switching to that soon. I'm not sure what I would use for extreme high temperatures (besides, my "extreme high temperature" is a nice cool day for Dasha).
Keep in mind that the CD4E transmission is known to be finicky about the fluid. Any time you stray from the Ford Motorcraft fluid, you run the risk of transmission failure. If you notice any bad symptoms like a bump stop, delayed engagement, or shifting flare, get the fluid out immediately and run Motorcraft fluid again for at least 10,000 km. Then you might try another brand if you're stubborn like me.
