When I changed mine some 30,000 miles ago I used Ac Delco Dex VI using Starless' initial DIY in conjunction with a few others. I had non of the symptoms recently noted with his current Tranny oil change. That being said most of the current makers of Dex VI are of the syn blend variety and it seems as though Valvoline is one of the few if not only maker of fully synthetic Dex VI. The remaining bottle of AC Delco Dex VI I have does not say whether or not it is a blend or a full synthetic. I'm not sure if this has any bearing on his issues whatsoever but just an observance on my part for the OP.