is this the correct auto transmission fluid?

[FR-S8N]

for 2005+ Mustang GT's?
How many do I need?

http://www.americanmuscle.com/royal-purple-max-atf-transmission-fluid.html

 

[Art161]

I don't know whether there were any changes from 2005 to 2007. For my 2007, it seems as though this would not be the correct fluid. The requirement is for 11.9 quarts of Mercon V, not Mercon.

 

[stang8urimport]

Yep. Do NOT mix Mercon with Mercon V.

 

[Art161]

Yep. Do NOT mix Mercon with Mercon V.

I know that you are not supposed to use Mercon when Mercon V is required. Can you top off a reservoir that contains Mercon with Mercon V or do you have to drain the entire system if you use Mercon V?

My reason for asking is that the production of Mercon ceased July 1, 2007. Ford says to service manual transmissions and power steering systems that used Mercon with Mercon V. I don't know whether they mean for a complete flush and fill or whether you can also use Mercon V to top off a Mercon reservoir.