Added to the FAQ thread.
In my MKIV, I am pretty sure that GTIMKV used Fuchs oil in it, but I am not too sure what grade.
My short addition to this is that if you are running a thin oil and the car is also running rich, you should be careful as fuel can make it past the rings and end up thining out the oil prematurely as well as damage the oil filter making it become more brittle and less effective.