2006 Pontiac Grand Prix 3800 Series III V6, 110K miles.

I just installed a shift kit on my car, and filled it back up with Dexron VI, since I saw it is often recommended for this car.

Last month I brought it to the mechanic to replace the transmission filter (and I thought he would’ve done the shift kit too), so I don’t know which type of fluid he used. I also don’t know if Dexron VI has become the mechanic’s norm for this car.

Did I just mix fluids, and if so, how bad is it, and what should I do?

The good news is that there are no apparent problems, the shift kit seemed to have helped (after a test drive this morning), and the month-old fluid was black, so hopefully it’s more red now.

Thanks for any help.