I will say that I have ran 50/50 of parts store brand coolant my whole life, and never had a problem. Last winter it made me consider if I was doing enough. Here in Minnesota, temps got below -30F a few times by me, and parts of the state went below -40F. I never had a problem, but I heard of numerous reports of cracked radiators, overheating, or other problems. Damaged heater cores seemed to be a big one. I am wondering if there is a coolant that is better than the rest in the cold temps. Another thing I was considering was running a mix of 60/40 to further reduce the freezing point. One thing to consider is it does get to 100 degrees often in the summer here. Am I thinking about this the right way, or should I just continue to run what I have been?