Back in the old days (circa 1960), a old hot rod trick was to put Type-F in your GM automatic tranny. Due to the different friction modifiers, Type-F would work in a Hydramatic or Powerglide to improve the firmness of the shifts, sort of like a pour in shift kit. You could not, however, put Dexron in a Ford Auto Transmission or it would slip.

Things have changed now, however. I'd run Mercon (not Mercon-V) in there if I were you. You might try some of the stuff they sell at auto parts stores that is supposted to help free sticky shifts (Lucas comes to mind). But FWIW, I've heard of people on here running 80W-90 in their M5OD for a while without major issues.

Also, a factoid most people don't know is that Ford recommended Type-F in their power steering units up until at least 1995.