I use one of those two buck floating ball testers, which is probably fine in a practical sense, at least for me. I do, however, like to do some experimenting from time to time. I discovered that when I pour 100% antifreeze into a small container and draw the liquid into the tester, all the ***** float, indicating freeze protection to -40 degrees. From what I have read, 100% antifreeze is going to have a much higher freeze point than that. Those testers must be testing for a minimum percent of antifreeze to float all the *****, but once it exceeds that point, all the ***** continue to float.

So here's a question (finally). Would a refractometer indicate the true freezing point?

Feel free to comment all you want about floating *****.

 

Saywhaaaaaaaaaaaaat?

 

That's what I thought. When I checked for replies, the plural of ball appeared as *****. Then later it appeared correctly. Maybe the computer edited the post and then a mod restored it to what I had written. I know it's kind of funny in some ways, but I couldn't think of a decent way to write it other than referring to the plural of ball. Lack of imagination on my part.

 

Hmmm...I don't know the answer to your question. I like to test my antifreeze on my enemies dogs. If they live, too much water in the mix.

Just kidding.

 

I think your talking about a http://en.wikipedia.org/wiki/Hydrometer. It doesn’t test the freezing point, it tests the specific gravity of the liquid (anti-freeze) to water. The meter you are using has been calibrated testing anti-freeze. It is gauging the ratio between anti-freeze & water. They also aren’t hyper accurate either. They are more of a ball-park number. I’m sure if you used three different testers you would get three different results. The freezing point of the various anti-freeze to water ratio’s is well known, so the gauge manufacturer puts markings on it that correspond to those ratios & freezing points. Make sense?

A refractometer won’t help you at all since it is dealing with light.

 

Where I live, 50 degrees F is freezing.

 

goes to minus 35 here
my garage stays at 15 degrees c all winter though

 

You are correct that a hydrometer measures specific gravity and they are not known for their accuracy.

From what I have gleaned on the Internet, an automotive refractometer does use light refraction to determine the freezing point of a mix of water and antifreeze. The ones that automatically compensate for temperature can be accurate to within 2 degrees F. They often have one scale for ethylene glycol and a different scale for propylene glycol.

The specs on refractometers seems rather scant. It appears that most of them read a maximum protection level of -60 degrees F for a mix of 70/30 antifreeze to water. Then the protection begins to diminish. The antifreeze manufacturers generally say that 70/30 protects to -84 degrees F. I did find a table somewhere on the Internet (I forget where) that said the maximum protection was -60 degrees F. I suppose if you live in a place where the temperatures gets lower than -60 degrees F, you don't need a different refractometer; you need a different place to live.

I also came across some other information. 100% ethylene glycol antifreeze has a freeze point of about 9 degrees F, and a boiling point of about 386 degrees F. But antifreeze has about 50% of the heat transfer capability of water. Also, if the antifreeze contains silicates, a concentration over 70/30 will possibly cause severe pitting of the water pump and engine.

If anyone has practical experience using a refractometer for measuring coolant protection, I'd like to know about it.

BTW, my first post shows up with the plural of ball as ***** if I am not logged in, but the post shows the word if I am logged in.

 

Unless you live in northern Cali near Tahoe, I wouldn’t worry about your coolant mix. A 50/50 mix will do just fine. If you do live up there then ask your local mechanics what they recommend for winter temps and run with that. You should be just fine. In REALLY cold areas people install block-heaters to keep the motor warm while its parked.