The previous owner may have used something other than the correct stuff. I have yet to see a used, old MB with the correct type of coolant - amazing. What's interesting is that I also replaced the radiator 2 years ago too (forgot to mention that). The entire cooling system (component-wise) is new. I don't know where this stuff has been hiding. I don't believe these had the silica packet. I replaced the tank and don't remember hearing that moving around inside when I walked out of the dealership.

What are the instructions with that acid wash? I have the MB-brand bottle of that stuff but there aren't any instructions.