Freezing Point - Best Mixture

[AKWRX]

The mixture freezing lists above appear to have been sourced from data using chemically pure water. Pure water with no ice nuclei to start the freezing process can be chilled to -40 before changing state to ice. In the atmosphere it is not uncommon to have "super cooled" unfrozen pure water at -15F, or colder in clouds. In the real world, alcohol/water mixtures contain many other contaminates that act as ice nuclei, so the practical freezing points are not nearly as cold as those listed. For example, windshield washer fluid with a 50/50 mix of methanol also has detergents and other particles that serve as ice nuclei. The actual freezing point would be closer to -20F, rather than the listed -65F. I have observed an 80/20 mix of methanol (in a not too clean can) cold soaking outside to have the water visibly start to slush up at only -70F. Also, note that there are typos on the methanol freeze points for the 70, 80, and 90 percent entries (100 degrees off).