According to Tremec, they found that Mobil 1 ATF can cause a shift "nibble" at cold operating temperatures which goes away when the ATF warms up. They highly recommended the non-synthetic Dexron III. weird.

 

OK, what the heck is shift "nibble"?

 

I have no idea, but perhaps they are using that to define grinding?

 

That sure does sound like what my GT is doing on cold mornings. It cleared up after I went 10 miles or so down the road. I had to shift in to second very slowly to keep it from trying to "grind" the syncs. It felt like the syncs just were not spinning up and were crashing into each other instead. After getting a bit of heat into the tranny, that went away.

Of course, I'm still not 100% happy with my second gear shift warm or cold.