[katy]

I used to have a very good anti-freeze tester, it had a float w/letters, a thermometer which showed the temperature of the sample and a chart where one crossreferenced the float reading w/the temperature reading to get the freezing point of the sample. I had it so long all the rubber parts deteriorated to a point where it was no longer usable. Tried to find a good replacement, but no success. I don't trust the ones w/floating balls or any of the cheap ones which it seems is all one can get these days.

Here's a chart, courtesy of Detroit Diesel.