Following on from http://www.audi-sport.net/vb/audi-s4-a4-a4-cab-b8-chassis/196048-stoopid-oil-levels.html, I was advised by Audi today that if you want to get an accurate oil reading from the computer you need to park the car on the flat. Turn on the ignition, but not the engine and wait around 5 minutes. The oil level bar should appear with the correct reading. If you think the computer is not reading properly, open and close the bonnet first. It resets the computer.