Recently, I took my 2002 e320 into the dealer for some radio work. When I picked up the car they told me that I had a small rear seal leak. I have not had any problem with oil usage. I do have a question about the advisability of their technique of pressure testing the crankcase. It would seam this would be hard on the seals as I do not believe that the crankcase is under pressure under normal operations. Does anyone have any experience with this testing technique?