ATD Tools 3705 Coolant Refractometer

Great tool to use for measuring anifreeze to water ratio. Confident that it will last in a home shop environment.

Without a refractometer how do you know the percentage of antifreeze in your system? Well, after flushing and draining your system you can look up the capacity of your system and add half the capacity and assume it’s a 50/50 mix. Did you flush out all of the old antifreeze?

Do you want to use a little higher ratio of antifreeze to water?

When you radiator is low, do you just add water or antifreeze or both? What’s the current ratio in your vehicle?

Why guess? This refractometer works well for me. I did make a small mixture of 50/50 and 60/40 and then used the refractometer to see that it reported correctly.

When I got my refractometer I saw a piece of lint in the image and couldn’t get it out. I contacted Amazon and got a replacement easily and painlessly.

In the past I’ve used refractometers for various purposes. This one has a nice easily readable display and scale.

8/11/19 - Update: still working great for me. In my latest car, my owners manual said my coolant system has 4.8 quarts, the shop manual says 5.3 to 5.8 quarts. How much do I really have?

After flushing my system with distilled water, and measuring the flushed fluid to have less than 5% of antifreeze remaining in it, I filled the system with my "best guess" amount of antifreeze and measured. I got a crazy low number with the refractometer and wondered why. It then hit me that some of the distilled water in the overflow hose backwashed into the radiator diluting the mixture where I took the sample. I then re-ran the engine with the hose cleared of distilled water, re-measured the antifreeze level, saw it was a little low, added more antifreeze, ran it again, and now I'm where I want to be.

The refractometer was still zeroed from my last use and is still reading great.

Every owner of any winterize device should own this refractormeter. Simple to use and powerful protection against freezing and bad costly information from others.

This is much more useful and accurate than the floating ball hydrometers. When I get a car with an unknown coolant maintenance history, I like to flush the system out with distilled water, then add half the coolant capacity with concentrated antifreeze to get a 50/50 mix of coolant and distilled water. The problem is you don't know how accurate the listed capacity is, and you don't know how much residual coolant is left in the system. This tool solves that issue. I tested it with distilled water (picture included) and then with a few different cars that I already knew the coolant ratio. This refractometer gave me the values I was expecting. I then tested another car that my ball type hydrometer was showing barely adequate freeze protection, and sure enough, it showed me to be at 43% antifreeze. With my ball hydrometer, I didn't really know exactly how low my ratio was. With this refractometer I could easily calculate out that I need to drain out 0.7 quarts and add that same amount of concentrate to get me to the 50/50 ratio.

The ATD refractometer lists the antifreeze % as well as temperature protection in degrees F. Many of them only tell you what the freeze protection level is, and you have to find a chart to determine what the ratio is. This is one of the reasons I chose it over similarly priced models. I like to be able to read the ratio directly without consulting a chart.

Nicely built and easily calibrated, easy to read the concentration. It's a much better approach than the little cheapie float units.