Sometimes the head gaskets will start to seep. They will not leak enough to hit the floor. In this case, I would wait for it to worsen. It is rare for them to mix the oil and coolant if the oil is seeping from the outside. I would ask to see the leak, then determine the severity.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS