It wasn't a Mercedes-Benz but in 1987 I bought a brand new Mustang GT. I found myself putting oil in it once a month and I'm talking like a whole Court. Well I called the dealership and complained and he said read your owner's manual. And sure enough and the owner's manual it said that one quart per 500 mi is not considered abnormal usage. I couldn't believe that. But sometimes you just have to add coolant to a vehicle. That's nothing to worry about if you just had to do it once. Now if you're having to add antifreeze once a month then I would be worried about it. It may be that the guy that looked at it just wanted to scare you to death enough to have you bring it to him and he can charge you an arm and leg to do it and not do anything at all. I would definitely get a sick and opinion before tearing into it that's for sure. Like I said just adding coolant one time is not something that's abnormal by any means.never add any oil. just one time for coolant



