the cap for the flush is in the lower hand driver side, its infront of the radiator, you need to take off the very lower driver hand side grille insert, it should have a little spot to put in a flat head screw driver. , once you have taken that off, you should see a red cap, you'll have to twist that off, and the ani-freeze should come out, audi tech's recomend glycon 12, you can only purchase it at the audi service department