I had a 1.8t B5 Passat (2003) and always used Mobil 1 0W-40 without any issues.
Try to use oils that have the VW502.00 approval on the label.
I think many oils that dont have it can be used without any issues however for peace of mind the Mobil 1 is readily available.
Also try to to get bigger sized filter, if i recall correctly those engines are prone to sludge, i used to buy a K&N filter and there were 2 versions, always buy the bigger one.
Cheers.