Nothing ever happened, no solids, no cloudyness, nothing exploded.haha We even heated up the coolant mix ( minus metal) in the micro wave to boiling point. We put broken pieces of aluminum casting from a smashed water pump, we added cast iron pieces, steel chunks, even put part of those gm plastic /rubber intake gasket.anything we colud think of to try and get this bad thing to happen by mixing coolant. We pulled some dexcool and some standard green coolant mixed them in a clear jar and left them on the shelf. Dont mix extended life with the green stuff, but no one could tell us why.

When I was working in a shop back when dex cool came out, we were all told the same thing. Its actually been a while since I've seen name brand glycol only coolants. Now there are long life coolants that supposedly mix with everthing (other Prestone products), however I have not used them. But I have not mixed them, so I don't know for sure. I have heard that it will cause solid particles to form and fall out of suspension, clogging passage ways and tubes. I have no idea what the effects are if you mix the two. Last year I replaced the Dex-cool in my 2004 GMC and the replacement coolant (Prestone I think) specifically warned against it. GM replacement Dex-cool currently does not recommend mixing coolant types. When red coolant came out, it was not at all compatible with glycol coolant as far as I understand. What is usually refered to as red is a long life oraganic acid based coolant (think Dex-cool). Fieldservicengineer is an expert in this, so I hope he weighs in on this thread.

Mixing green coolant