It tests with my coolant tester, so I assume it must be ethylene glycol. Hard to be believe that the 80 year old farmer that owned it before me used BMW coolantin it. Maybe his garage convinced him it was better than the good old green stuff. My goal was to lower the freeze point below the +10 degrees that it tests at now. Am I going to screw anything up if I drain the radiator and add Prestone to get the freezing point lowered?
