Learn more physics!
Why wouldn't sodium chloride be used in commercial antifreeze instead of ethylene glycol?
I assume your idea is to add sodium chloride to water and use that as
an antifreeze because the freezing temperature of the solution is lower
than that of pure water.
One big problem in automotive cooling systems is caking up of
deposits inside the radiator and other piping. You may live in an area
where teakettles and water heaters cake up with salts which get left
behind when the water boils away -- the same thing can happen in a
radiator. Adding salt intentionally seems to be just asking for this to
happen. Also, salt accelerates the formation of rust.
p.s. I also think that the lowest freezing point attainable with
salt may not be low enough. The problem is that there's a maximum
concentration before the salt starts to precipitate out. And again, the
corrosion problem is significant. Mike W.
(published on 10/22/2007)
Follow-up on this answer.