Well... Its new for us, than mostly, all is better than dino 80W-90?
"Guidelines" of my gearheads:
- Ditch 80W90 if you not in a country with lowest temps in winter around 60°F (Arabia/Africa regions). Use 75W-90.
- use 75w90 at stock cars
- use OEM 75w110 (or your own 60:40 mix of 75W-90 and 75W-140) if your car is tuned and has 75w90 OEM fill.
- use only 75W140, if your car manufacturer says, you must unexceptional use such oil or if you have Ubertuning
- change MT and FT oils between 43.000 and 48.000 miles, if your car manufacturer speak about "lifetime fill"
Very simple recommendations
But efficiency is not all about it. Wear protection is the other side, then repairs of all kinds of gears are ever expensive. For example, 70W or 75W in MT is FOR ME not the solution, if I can find 75W-80 GL-4(+) than works (I have).
Similar for FT or angle gears (AWD). 75W-90 with maybe littlebit lower Brookfield as another, is for me always better trade-off as manufacturers efficiency experiments with 75W85.
But commonly I self use standard 75W-90 for OEM stock cars without study and comparison Brookfield.