Brake Fluid Tester Pen, Hydraulic Fluid Liquid Oil Moisture Analyzer with 5 LED Indicators, Auto Brake Diagnostic Testing Tool for DOT3 DOT4 Brake Fluid

It just works as described. You put a AAA battery in it and push the end like a pen, which turns it on with a green led. Insert it into your brake fluid reservoir and it gives you a reading by the color coded LED lights on the side. I like this one because it works with different brake fluids dot3,4, etc. They may all do that but wanted to be sure before buying and this one had it in the description. I have used it on two vehicles so far and it works great! I found that I needed to change the fluid in one of my cars which probably saved me a lot of money already, because the fluid can retain water and start to deteriorate your brake lines and parts. This tester does seem to be a high quality piece of equipment like something an actual mechanic would use often

Works exactly as described! Great value for the price. My only complaint is I had a hard time opening the battery door and it feels like it might break one day, but for how often I will be using this product its great and works perfectly.

Brake fluid tested works as intended. It is not complicated, and as soon as you dip the probes to the brake fluid you got the ready. It does not record the reading, and unfortunately it works fine, and there is no need to get an expensive one, especially if you have one or two cars to test.

Popped a AAA battery in and tested in a cup of water. It instantly shined red and indicated 4%. Next tested the brake fluid in my 2016 Nissan Rogue and it showed as 1%. Using a baster, I extracted a small amount and squirted it into a small cup. Added a few drops of water with a thin syringe and the tester still said 1%. Added another tiny amount of water and it jumped to 4%. These readings were very consistent. I'm satisfied that the tester is accurate. Not surprised that my 51,000 mile vehicle driven gently in the arid U.S. Southwest tested as only 1%. Maybe vehicles in humid environments need frequent brake fluid changes but I don't believe that's true for those in the desert. That's why I bought this tester after the local Nissan dealer tried to sell me a brake fluid change and other service. Dealers and most shops can only be trusted to try to get as much money out of us as they can con us into losing. My fluid is still very gold in color and my brakes work perfectly, so I'm opting to not change it at this time. Will test again next year. When it makes sense to do so, I'll change it myself.

The product works well enough but is pretty much flimsy junk. As has happened with most other people, the plastic around the terminals appears to seize onto the cap so that when you remove the cap, even with minimal force, you end up breaking off the entire head. This all happened despite storing the tester inside and cleaning off ALL residual brake fluid after each use. I did get a couple uses out of it and it appears to do a decent job reading brake fluid, but it appears to be inevitable that after a few uses it will completely break apart.

This is basically a continuity tester set in an easy to read led set up. Once the battery (1AAA) is installed the cap on the probe end is removed by pulling it off, then press the button on the top of the tester near the pocket clip, with the master cylinder cap, slave cylinder cap or whatever reservoir cover containing brake fluid is removed, simply dip the probes two metal tips into the fluid and the led’s will go from the green light for good / safe to either yellow or red depending on the amount of moisture contained in the fluid which will indicate the need to change the fluid or not. SIMPLE !!!!

I have a small fleet of vehicles that I support for family and this is something that lets me get ahead of any issues with old brake fluid. I've tested it with pure water and new brake fluid as well as my vehicles. Water tests bad, new fluid tests perfect and my vehicles show some but well within acceptable range for now.

Update 8/2024: So its about 5 years later. Mine finally broke near the front probe plastic despite always cleaning it after use. I was able to repair it with superglue but that is beside the point. I think the plastic cap is partially to blame as it tends to get stuck and is way too tight. I would suggest trashing the cap and just use the packaging the item comes in for storage. I've downgraded the product to 4 stars from 5. This product works great. I tested it on new brake fluid and on a cup of water to see if it really worked and it does. Similar products customers have complained about the plastic around the probes breaking off over time. My advice here is to always clean the test pen with denatured alcohol after use to help remove any trace of brake fluid on the surface. Doing so should really help extend the life of this tool.

this product does what it was made to do, happy with it

Small portable easy to use

Unit arrived fairly quickly and was not damaged. I tested its operation in a glass of water first; it displayed the highest moisture content (>4%). I used it to test the fluid in my 2 cars and both cars showed the first moisture content display (<1%). It's reasonably priced and seems to do the job. Needs 1-AA battery to operate, which is not supplied.

Da dies bereits das zweite Gerät dieser Art ist, das sich bei mir im Einsatz befindet bin ich sicherlich nicht komplett neutral. Das Gerät zeigt anhand vorhandener LED's die Stromleitfähigkeit der Bremsflüssigkeit an. Diese erhöht sich je mehr Wasseranteil sich in der Bremsflüssigkeit befindet. Durch einen erhöhten Wasseranteil leidet die Viskosität, was schlussendlich zu einer schlechteren Bremsleistung führen kann. Da die Aufnahme von Wasser durch erhitzen der Bremsflüssigkeit erhöht wird, ist diese Gerät ein gutes Mittel um nach größeren Touren und außerhalb der Wartungsintervalle die Bremsflüssigkeit auf deren Zustand zu prüfen. Es erfüllt seinen Zweck und ist leicht zu handhaben. Der Preis ist in einem vernünftigen Verhältnis. Meiner Meinung nach ein Werkzeug das in jeden Motorradfahrer-Haushalt gehört.

A Caneta de Teste de Fluido de Frei é um acessório indispensável para quem deseja realizar a manutenção de seu automóvel a nível amador assim como aos mecânicos profissionais. Fantástica!!!