Coolant: how to measure ratio water-coolant

dejongmc · Post by **dejongmc** » 21 Sep 2010, 06:50

Due to a little leak I had in one of the hoses from my cooling system, I added purified water or Zerex G5 to it, but by now I do not know if I have the right ratio of 50%-50% anymore.

Is there an easy way to measure the water-coolant ratio?

Retired MVS Contributor · Post by **Retired MVS Contributor** » 21 Sep 2010, 07:44

There are inexpensive hydrometer type tools for measuring that available at Autozone, Autobarn, etc...It measures the specific gravity...

nightc1 · Post by **nightc1** » 21 Sep 2010, 13:27

Yeah an anti freeze tester tool is the best one for the job. It'll tell you what temperature your car is good for. 50/50 is ideal but not a diehard requirement. Colder climates may require closer to a 60/40 (Coolant/Water) blend. Most stores have testers for $1 to $3 with the $3 one looking fancier but doing the same job as the cheaper ones.

As a side comment, in the future... pre-mix for adding coolant/water. You can buy antifreeze that is already 50/50 mixed, or mix anti-freeze in a separate container with distilled water that has a clearly defined 1/2 way point. It doesn't have to be perfect or anything... but if you are adding to a system that already had the stuff mixed up really well... then you lost the mixture of ~ 50/50 and your current mixture ratio is still ~ 50/50.

A 50/50 mix has freeze protection down to –34°F and boil-over protection up to 265°F . I'm saying that so if the tester only shows the temperature it's good for and not the mix % then you can see an approximate target.