I went to my local Merc Dealer to get the "recommended" coolant for my 300TE. However when I asked the head mechanic there he told me that because my system is completely drained (I did the headgasket) I could use the Green coolant. He simply instructed me to not mix it with Orange which I already knew. He stated that all of the gaskets/parts will not be affected by the green coolant.
What do you all think of that? Every forum I have read says to not use the Green coolant, but if it is safe for Aluminum parts and more readily available than the Zerex (in my area at least), why not?

Also on a side note: what is the best way to flush my system to make sure I get any leftover junk (or oil that was in the coolant)?