My little reference book states that
30% antifreeze will freeze at +4 degrees F,
40% = -12,
50% = -34,
60% = -62 and
70% = -84 degrees F.
(Any more antifreeze and the freeze point increases!) I use 50%.
More importantly for this discussion, “Commercial automotive antifreeze...”
(ethylene glycol) “increases the temperature at which the water will boil.
At a radiator cap pressure of 15 psi a 50% solution...will increase the
boiling point to 265 degrees F and a 70% solution will increase it to 276
F.”
But I would also check your mixture and timing, as they have huge effects on
running temperature.
Also, remember that antifreeze is the lubricant for the water pump, and
contains a lot of anti-corrosion additives to avoid that brown water
syndrome. Always calculate how much antifreeze to use from the stated
capacity of the cooling system, not just how much water you can put in
because you will always have a lot of water already in the block. Always
flush the system every year or two with lots of clean water to get rid of
all the old water. I also use deionized or distilled water when I can -
have had vehicles go more than 230,000 miles without rusty water or even
touching a radiators.
Frank ‘59 TR3A
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