Focusing on how/where I learned the answer to the best EG/water ratio, I just read the bottle. 50/50 recommended for most areas, ratios up to 70/30 recommended for extreme conditions.

In my(admittedly limited compared to many here)experience, the ratio is pretty moot for cooling provided the cooling system is in sound mechanical condition. I've had no issues with straight water at 100+ deg temps. If you're relying on your radiator fluid mix to prevent boilover, you likely have other mechanical issues you should resolve, regardless of your mixture.

Much more important is freeze protection in the short term, and corrosion protection in the long term.

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617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap