Most people never think about their valve stem caps. They just sit there, keeping dust, moisture and road grime out of the valve. But if they're missing or cracked, that gunk can build up and cause a slow leak over time. Small part, real job.
The genuine Audi 80A071215 caps are anodized aluminum with a lacquer coating, so they won't dull or corrode. What actually matters here is the plastic thread inside. Plain metal caps - aluminum ones especially - can seize onto the valve stem after a year or two outdoors. Aluminum against a steel valve stem plus a bit of moisture, and you get corrosion welding the two together. We see this a lot. Then you're stuck fighting it with pliers, sometimes damaging the valve itself. These don't have that problem, and they're safe with TPMS sensors, which most modern Audis have.
If you're running plain metal caps instead, especially aluminum, a little grease on the threads before you install them saves you the headache later.
