Hello,just change trans fluid in my wc t5 and refilled with just a basic oreilly dexron 3 atf fluid.it seems like the trans is shifting alittle bit harder than before the change?i know it was atf that i drained out cause of the red color.is there a better atf to improve the shifting??is synthetic better??has anyone had the same problem but fixed it with an additive??i was reading a couple threads about people having vibration at high problems,i had the same problem.new u joints and balanced driveshft now smooth as silk thanks

 

No, synth won't really change the shifting. AA;; ATF is going to be pretty much about the same in that regard.

You might want to try the GM "Synchromesh" fluid.

Back "in the day", I always used to run half-&-half ATF & STP in my Muncies and T-10s; but I've never tried that in a transmission with composition blocker rings such as the 2nd design T-5 or the T-56.