One knowledgeable bidder flags the rear main seal as a known issue on R129s, especially 1998-2002 cars as they age and accumulate miles, along with oil separator, cam plugs, valve covers, and oil filter housing/cooler gaskets. Sellers commonly report valve cover gaskets and rear main seals already addressed on well-kept examples.
Engine oil leaks: rear main seal and gaskets on 98-02 cars
Mercedes-Benz SL (R129) · mechanical