[s-cars] Coolant compatibility?

[Jim Fleischer]

Hey guys,

So, I need to top off my coolant reservoir and I have run out of what is in there already.....good ol' Prestone Green ethylene glycol non-premix (I'd rather mix my own.)

Well, seems like I can't find Prestone anywhere in NW Montana, so I've got a choice of some other stuff like Zerex, etc.  With all of the different coolants out there, does any "green" colored coolant work with the Prestone I've already got in there?  I know these finely engineered machines like their fluids juuuuuust right, so I don't want to "f" something up by adding something that will not mix in right.

Thanks! 

Jim Fleischer
'95 s6 avant
'83 ur