I am looking at a 2000 a4 1.8t with about 180,000. Guy said he always used regular oil for last 30.000 miles. The pixels in the cluster are almost dead but there is a yellow light that comes on but can't tell what it is. No owners manual either.

Is the oil pressure light that has to do with sludge on the center display that always burns out? If it is how can you tel, what the light is or at least tell if it is the oil light?