[DorkMissile]

I haven't used the Redline, but I have used Syncromax and Amsoil ATF, and for me the Amsoil seemed to feel smoother longer. I think both felt the same new, but the Amsoil felt the same at 5000 miles as it did new.

Just dont overthink the whole thing - GM didn't design this trans, Tremec did. Its the same transmission for all cars that use a TR6060 (GT500, GT350, Viper, Challenger, etc......), the only reason GM recommends using the temp sensor as the drain plug is that they didn't want to redesign the cross member.

Both will get the fluid out. You would get a little bit more out of the actual drain plug, but it is maybe 2oz more. There is much more residual fluid in the lines, cooler, and pump (there is a actual fluid pump in the front of the transmission that is used to cycle the ATF around the car - it is actually shipped to the cooler in the front to cool, and then shipped to the differential in a heat exchanger to lower the temp of the rear diff)