My Mercedes-Benz service agent here in New Zealand uses and recommends Mobil One coolant, which is green. They also use Mobil One oils and other lubricants.

I have to say that I am suspicious of claims that the only fluid to use is the proprietary orange one. I suspect that oil giants like Mobil put just as many (if not more) research dollars into antifreeze formulation as M-B do.

And after all, aluminium is aluminium. Many, many engines are aluminium: it is nothing unique to Mercedes. Even Honda engines are aluminium!

Just my 2c worth ...