I agree with old sinner, but 99 times out of 100 is the Benz found with green or orange used tap water is used too, and that is a big no no....Tap water is the killer to any aluminum engine leading to head gasket issues. Distilled water to fill the radiator and clean. This is also true for any Aluminum head to cast-iron block GM, Ford, Chrysler, etc...

The green stuff is better than the orange stuff, but better than the clear stuff. I do not know. Now Mercedes changed the coolant it is blue, I think...

Coolant and Cap need to be changed about every two years.

Martin