I agree. It is most likely the oil gaige leaking from the instrument cluster. I had this same problem on my 300TD, only it looked like it had been leaking for years! My floorpan and carpet were covered in oil when I bought the car. It is easier to simply replace the cluster with the gauges on it, than to fix the gauge itself. Once you remove the cluster, you'll see what I mean.

You should be able to find a good used cluster on ebay for under $50.

Good luck to you.

__________________
Sean Roland

2004 Saab 9-5 AERO 138k (for sale)
2000 VW Jetta GLS TDI 215k (sold)
1999 Toyota Tacoma 4x4 - 132k (sold)
1999 Saab 9-3se -- 84k (sold)
1986 MB 190e 2.3 16v -- 221K (sold)
1985 MB 190e 2.3 16v euro -- 145k (junked)
1992 Saab 9000t 5sp. -- 142k (sold)
1994 Subaru Legacy -- 264K (sold)
1998 Audi A4 1.8TQ -- 102k (sold)
1983 MB 240D stick -- 160k (sold)
1988 Saab 900SPG -- 156K (sold)
1983 MB 300D -- 270K project or parts (sold)
1986 MB 280SE Euro stick -- 150K (sold)