I know dex 3 and 6 are the best but I got 2 gallons of full syn atf from work so I figured I might as well use it on my next pan drop. I have about 250 miles on since I did this and now it is starting to slip into 1st and 2nd. im thinking I made the wrong choice or is my trans on its way out. it has 138000 on it and it was running great before it did this. what do you guys think? is it possible? the mods listed below are not on the car I am using or having the problem with. its on my dd.