Replaced the PCV valve, or Oil Separator as Audi calls it today. Very easily done as all that needs to be removed is the coils on cylinders 3 and 4 and about 8 triple square screws. At 73k miles the internal parts looks very good. 10k mile oci and Ravenol RUP 5w-40 seems to be agreeing with the engine. Took about 40 minutes total.