How do I change the Audi A6 Differential Gear Oil?

I recently noticed some strange noises coming from my Audi A6's differential, and a mechanic suggested that I change the gear oil. How do I go about doing this and what kind of gear oil should I use?

To change the Audi A6 differential gear oil, first locate the differential drain plug and remove it. Allow the old oil to drain completely before replacing the plug and filling the differential with a gear oil suitable for your specific A6 model. Refer to your owner's manual for the recommended oil type and capacity.