No, the car has a 195 degree thermostat and it doesn't run any cooler. I didn't expect it to run any cooler after the flush - I just wanted to get 34 years of crud and rust out of my engine block. I've previously restored my cooling system with all new components (thermostat, stat housing, all hoses, water pump and drive belt, heater core, all clamps and recored and rebuilt radiator as mentioned earlier). And yeah, I can see your point about using distilled water. All I know is that I've been using tap water from my home for the past 34 years and have never noticed any contaminant buildup in my cooling system. Maybe I'm just lucky but I've had excellent results with tap water and Prestone II (or the equivalent NAPA antifreeze).