Changing the rear diff oil soon and sounds like most people on the TT forum put 1 litre of oil into it. Audi have just told me the correct amount for a 1999 8L S3 is 0.5 litres. Anyone measured the amount of oil thats come out of their rear diff when changing it to confirm quantity? Good how to here:Differential Oil Replacement album | mcphill | Fotki.com, photo and video sharing made easy. ps They did confirm that the diff oil is different to the gear oil which some have asked about - two different part numbers.