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Best Antifreeze Hydrometer

Without coolant for your car, you will quickly run into problems. It is therefore all the more important that there is always the right concentration of antifreeze in the cooling system. Otherwise, the coolant will freeze in winter and the engine will run hot within a very short time despite low outside temperatures. In addition, the antifreeze protects against too rapid wear due to deposits of rust and lime.

With an antifreeze tester, you can check the concentration of antifreeze based on the freezing temperature.

We’ll show you how antifreeze testers work and what to look for in an antifreeze tester test to make sure you actually find a good model. We also answer the most frequently asked questions about antifreeze testers.

Coolant tester is not only suitable for coolant. You can also test windshield washer water or solar heating systems with certain products.

Coolant Testers Car Best Choice

Best choice

Astro Pneumatic Tool Universal Radiator Pressure Tester

Removes odors and Moisture by filtering purifying odors, bacteria and allergens, and harmful pollutants, eliminating them at the source, it wouldn’t add harmful chemicals to the air. Prevent mold, mildew, and excess moisture.

5,0 Rating
Find Leaks instead of creating them
1pc Blue Test Adapter and 1pc Black Test Adapter to test original cap leakage
Radiator Purge and Refill Tool
Gauge – Test Range 0 – 35 psi (0 – 2.5 bar)
16 pieces Radiator Tester Caps

How To Choose Coolant Testers?

How to choose coolant testers

Best 5 Coolant Testers


Astro Pneumatic Tool Universal Radiator Pressure Tester

  • Easy testing for leakage in the radiator system.
  • With Temperature Gauge.

4,9 Rating

Check Best Price


4-in-1 DEF Antifreeze Coolant Refractometer

  • Measuring Range: -50 to 0 ℃
  • Diesel Exhaust Fluid, Battery Acid, and Windshield Washer Fluid.

4,9 Rating

Check Best Price


ABN Deluxe Antifreeze and Coolant Tester Hydrometer

Very powerful grade a silica
Capable of holding up to 800g/l of moisture

4,8 Rating

Check Best Price


OEM TOOLS Professional Series Ethylene Glycol Antifreeze Tester

  • Disc-type tester is accurate at all temperatures
  • Works on any vehicle

4,5 Rating

Check Best Price


Performance Tool Pro Anti-Freeze Tester

  • Easy to read scale & pointer
  • Freezing to boiling points for anti-freeze, calibrated in °C and °F

4,5 Rating

Check Best Price

We have tested the Best Coolant Testers for Cars and selected the best products for you.

What you need to know

Antifreeze testers are not only suitable for the motor vehicle but are also important for the regular maintenance of heating and solar systems. An antifreeze tester must therefore function reliably first and foremost. Whether the measurement results are also reliable and how the quality can be assessed as a layman is not obvious at first glance. Different types of antifreeze testers often do not make matters any easier.

To prevent damage caused by frost, you depend on a good tester. With us, you will learn about the different types and designs of antifreeze testers. With our tips, you will also learn important things about the proper use of antifreeze.

Check Antifreeze

Equipment and types of antifreeze testers

To check the amount of antifreeze in your car’s coolant, you have a choice of two common types of testers. The first is a container in which the measuring mechanism and a suction ball are integrated. This design also often has a pre-mounted suction hose.

A second widely used design is the antifreeze tester as a pipette. This compact design consists only of a tube with a suction ball and is therefore quite simple.


  • No suction hoses necessary.
  • Easy handling.


  • Somewhat lower measuring accuracy.
  • Only one scale.

While antifreeze testers are not all-rounders, but rather devices designed for a single task, the individual models nevertheless offer various features that improve measurement, handling, or even safety when using an antifreeze tester.

What to look out for:

Function Description
  • Measures the freezing point
  • Scales in Celsius and Fahrenheit
  • Can be used with coolants and sometimes windshield washer fluids
  • Eyelet for hanging
  • Prevents the tester from dipping
  • Alternatively plastic rings for pipettes
  • Impact-resistant housing
  • Shatterproof glass
  • Hydrostatic spears to prevent backflow

Use of antifreeze testers

How to use an antifreeze tester correctly

You don’t have to be an expert or an automotive mechatronics’ technician to check how much antifreeze is in your radiator system. You just need to have a proper antifreeze tester and know where the valve for your car’s coolant is. This is located under the hood above the reservoir for the coolant. Make sure the priming ball is compressed before dipping the hose or tip of the pipette into the valve.

If you then slowly aspirate the liquid until the measuring chamber is filled, you can read the specified temperature value directly on the scale. The tester must then be cleaned again. Avoid contact with the cooling liquid. Ideally, you should wear protective gloves during the measurement. This is also recommended by most manufacturers. The perfect value on the scale is between minus 20 and minus 30 degrees.

Antifreeze tester for solar systems

Solar systems for heating systems work with a carrier fluid for transporting the heat to the water tank. To protect the solar system during the cold winter months, and antifreeze must also be added to the solar fluid. Using a special antifreeze tester for solar fluid, the concentration of the antifreeze can also be measured here.

Heat transfer fluids such as Antifrogen have by themselves the property to protect against frost and corrosion. However, regular measurement is still advisable, as damage to older heating systems is annoying and expensive.

Tests of antifreeze testers as a buying guide

Testimonials are also important

Whether you need a tester for radiator antifreeze or windshield deicer, tests and comparisons can help you in your search for the best antifreeze tester. The only important thing is that certain specifications are not missing from the test. These include:

  • Material.
  • Design or category.
  • Temperature range.
  • Scales (Celsius or Fahrenheit).
  • Hanging function (Yes / No).
  • Price.

Best engine coolant

Air bubbles lead to incorrect measured values

The most important thing for you is accuracy, because what good is a nice device for you if you can’t do anything with the measured values. For this purpose, it is important that no bubbles form while you are aspirating the liquid into the measuring chamber. If this is the case, measurement errors will quickly occur.

As long as the engine of a car is still warm, the cooling system must not be opened under any circumstances. Otherwise, hot water could escape due to the existing pressure and scald you.

Likewise, an antifreeze tester should not lose any liquid when testing the coolant or windshield washer water. Otherwise, the measured value may also change. In comparisons of antifreeze testers 2021, some manufacturers can score points with so-called temperature compensation. This additionally increases the accuracy of the measurement.

FAQ – Antifreeze Checker

Are there also antifreeze testers for the windshield washer system?

Although not all antifreeze testers are suitable for the windshield washer system, the corresponding products are also explicitly labeled as “suitable for the windshield washer system”. Indeed, it is important that a tester is designed for the properties of windshield antifreeze.

How does an antifreeze tester work?

An antifreeze tester is normally a so-called hydrometer. The function of the hydrometer is based on Archimedes’ principle, which states that a body is only immersed in a liquid until the weight of the body corresponds to that of the displaced liquid. Because the density changes with the tested liquid, this property can be used.

In antifreeze testers, the liquid is drawn into the instrument through a pipette or suction hose. Depending on how high the concentration is, a temperature is displayed on the scale.

What else can be used to measure the antifreeze?

An alternative to the antifreeze tester in the form of the hydrometer is a so-called reflectometer. A reflectometer as an antifreeze tester also measures the proportion of radiator antifreeze or windshield antifreeze. However, the so-called “refractive index” serves as a reference for this measuring instrument. The speed of light in a vacuum compared to a liquid is assumed.

The actual test is simple and no more complicated than using a normal antifreeze tester. Using a pipette, place a few drops of the coolant or wiper fluid on the prism of the reflectometer. If you then hold it up to the light, you can read the measured freezing point on a scale.

David Muench (Carnes Mechanical)

David Muench (Carnes Mechanical)

Hey, I’m David. I’ve worked in a cars store for 6 years. I write reviews and guides, helping people to choose the most suitable technicals and best product for them. I’m happy to finally share my knowledge of the industry here, on CarnesMechanical.

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