The drivetrain drag due to thick oils is more pronounced on vehicles such as large 4x4s where you have multiple gear boxes. I put 140wt oil in my transmission, transfer case, and rear end a long time ago. Happened to do it during a real cold spell too. The vehicle would barely even roll down a hill on its own
I went back to the 85-90 wt and it was much better. I suppose switching to synthetic would help even more however I haven't driven that vehicle on the road in several years so I won't bother (in that vehicle at least).
IN my honda hx I used the factory honda MTF (manual transmission fluid) cause that's what seems to work best and is recommended by Honda. That's the only gear oil in the car too...about 2qts compared to about 2 gallons in the aforementioned 4x4.