On the manual box, well my car has only run just under 30K in 12.5 years (!!!), so all I've ever done is to check the oil level and topped up using the correct VW Group oil - one comment though, as the rear diff outside area is still completely dry, I was a bit lax in checking the oil level in the diff, but when I did, that rear diff housing needed maybe 0.125ltr to bring it back up to the "over flowing" state, I didn't expect that! The 6MT box only needed a "spot", ie I could have just left it as it was, but as I'd made the effort to buy both of these oils, I felt the need to use them! So, did Audi fill that rear diff correctly at initial assembly?