Thanks for clarifying! It was the 2nd gear blocker ring that I had to replace in the T5 in my old Isuzu because the clutch material was worn out. As for the needle bearings, I was repeating what I read on the instruction sheet that came with the parts for it.I've used and seen thicker oils with needle bearing transmissions with out issues (Porsche 997 GT3). I would be surprised if the needle bearings can't handle the thicker oils.
I have heard about the syncro material question. I read that this was an issue on older Tremecs.
Are you saying the syncro cones are made of AT clutch material? I have only seen the friction material deposited onto the surface of the blocker rings before.