[wiswind]

The TSB is 06-14-4 issued July, 24, 2006

It is still OK to use Mercon, but FORD discontinued licensing Mercon as of July of 2007.
They say to use Mercon V in all vehicles that specify Mercon.

This is why you now see Mercon V specification, and the recommendation for use in Mercon Specification on ATF labels now.

It is very understandable that your shop would not want to put Mercon V in if they are not aware of this latest TSB....
FORD has issued a few TSB's in the past that say NOT to use Mercon V or a product that is listed as Mercon / Mercon V in Mercon applications.

This TSB, 06-14-4, supersedes those earlier TSB's.