I've had my Evo in to the dealer for a couple of leaking axle seals and this last time I noticed a strange phenomenon. Immediately after leaving the dealership, the transmission shifted like a knife through butter-- that lasted all of a few miles then it was its usually notchy self. It's been cold here, in the 30s, and whether trips are short or long, the transmission stays notchy. Then, this morning, with temps in the 40s, the transmission was much smoother again all the way to work (just a few miles).

Any theories? I have a slow leak again but no more than a drop overnight- I doubt that the transmission is low on fluid. And as for the fluid, I have to assume (always dangerous) that the dealer is using decent stuff, Diaqueen probably. Is Diaqueen, for example, known to contribute to the notchiness of the transmission in cold temperatures?