I used a hydrometer to test the protection level of my new coolant (flushed this past weekend) and I have a question. The freeze protection is reading 0 degrees farenheit and the boil over protection is reading around 225 degrees farenheit. Am I OK with these values? The indicators on the side of the hydrometer say recommended levels of -18 degrees farenheit and 270 degrees farenheit. Should I drain some fluid out of the radiator and add some coolant only to bring the levels up?

 

Steve,

Hydrometers measure specific gravity. Specific gravity is extremely temperature dependent. The same sample which is read at 150 F will read as having a 30 F better freeze point protection level than if it is read at a temperature of 100 F.

Hydrometers only work for the ethylene glycol based antifreeze coolant. Propylene glycol cannot be read with a hydrometer due to the fact that up to 70% concentration specific gravity increases, but above 70% specific gravity decreases. A 100% of propylene glycol solution reads identical to a 40% solution. It's weird that way.

I would suggest you find an anti-freeze that is rated to a temperature range that you feel comfortable with for Bethlehem, GA. I don't imagine it gets below 0 F very often there, if it ever has, so I would think you would be fine. Now if you lived in Montanna that would be a different story.

 

I used the Toyota red coolant and mixed it at a 50/50 ratio as indicated. My wife has a Corolla which I also flushed and drained this weekend and hers reads -10 and 260. Just trying to be cautious

 

bump