Hmm my guess is that he is using an alu radiator and no proper coolant. 4 months is an extremely short amount of time for that much nasty corrosion... if that's the result of the GTX alone then a lot of people are in trouble.

What troubles me is that we can never conclude if and when alu will be a problem. There are those who never have an issue but others who have a hell of an issue. So which one is it?

After seeing these picts and all the bad propaganda in general I personally prefer trying to avoid aluminum, but, the uncertainty remains.