What vehicle are we talking about?
Just knowing that it takes Dex VI I'd say go ahead and Do it.
I have it in my wife's 2004 Nissan Xterra that calls for Dex III or Nissan Type (something), the Valvoline High Mileage Dex/Merc works like a champ in it.
Now that I think of it I have Lubegard Red in all my vehicles, 2002 Ford Taurus, Nissan Xterra, Ford F150. I havent had any issues with any of them.
Considering I have 209k miles on the Taurus, 88k on the Xterra, and 115k miles on the F150 (much of it with a boat), and all original transmissions. I'd think I'm doing something alright.