Mistakes were made

2004 Buick Century. My tranny fluid cooler line
disconnected and dumped out all my trans fluid.
Didn't know a mechanic in the area and a friend
told me he was pretty sure all ATFs are the same.
He was wrong. So the car has a single quart of
idemitsu type J in it that I used to limp it home
about a mile because it was gonna be towed if I
couldn't move it. If I fill it back up to normal with
DEX VI will the transmission be okay, or do I have
to drain it first?