The grades below are as BMW spec for the 335i, so check your grade spec for your gearbox and diff,
The brands below are top quality full synthetics, I used them after reccomendations on here:
Gearbox oil - 2 litres of Fuchs TITAN SINTOFLUID SAE 75W-80 synthetic
Diff oil - 2 litres of Fuchs Titan Race SYN 5 75W-90 Fully Synthetic Gear Oil
After changing the box oil I really noticed an improvement in shift feel and smoothness.