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

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.

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.

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.

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.

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.

Works well. Works with my 1998 buick lesabre custom. Hasnt broken on me at all like others have mentioned. Used it several times.Risk you take with any cheap product might not be very good or break easy. Hope its never the case with mine. I knew mine had to be replaced soon since i had it flushed out entirely 3 years ago so it was expectant where the % is. Easy to use for dot 3 brake fluid on my car. You take a risk buying anything these days but for about $10 worth it.

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.

Very accurate