Hello Tim,
The 30.000 Km ATF change interval I found on the 2 "Inspection Service" sheets included in the RLF (in english : Workshop service manual). And you are right, nothing is said about the strainer/sieve. However, on these very sheets two different gearboxes are mentioned, with different oil change intervals of 30.000 and 60.000 Km respectively. The gearboxes have codes "Audi V8 018" and "01L/01V". What is the difference ?
Regards, Eric