Before you tear into this job, have you modified your oil charge from the owner's manual recommendation? There was a tsb some time ago directing owners to refill the oil to 7 liters - not the 7.5 liters indicated in the manual. This was because 7.5 liters was too tough on the main seal. I believe 7 liters is about midway between the FILL and ADD marks on the dipstick.

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95 E320 Cabriolet, 169K