[s-cars] Internal fluids - again

[Aaron]

Hi all
With this colder weather it is time to get to my gear fluids
Anybody use BG products in their Audi's?
I seem to remember a post flaunting BG synchroshift for our transmissions
Problem is the BG people dont recommend it...
They say use their Ultra Guard product which is a 75-90 GL-5 rated
synthetic.  They also say it can be used in GL-4 applications. ....
Can anybody please confirm:
Trans- GL-4 ONLY, 75-90wt, 2.9liters - How important is the ONLY?
Diff - GL-5, 90wt, 0.8liter.
Thanks
Aaron