KAIWEETS Brake Fluid Tester Pen with Corrosion Resistance Probe, High-Precision Brake Fluid Moisture Tester with Data Hold Function, Buzzer Alarm, 3 Colors Backlight, Calibrated for DOT3, DOT4, DOT5.1

This is a quality tool that’s easy to use and works well.

This is a must have tool if you are available DIYer or a pro! Honestly I was a little skeptical. So I used the tester on both of my cars: one that recently had the brake fluid replaced and another that had no brake fluid replaced for several years. The tester really works!

Tests great. Very convenient. And it’s accurate.

Over the years, admittedly I haven't been good about changing brake fluid. Normally I would only add when low as pads wear down, or change it out when changing brakes, or if it looks dark. But I've been reading more about the importance of keeping brake fluid fresh, as it absorbs moisture over time. When brake fluid absorbs too much moisture, you won't likely notice under regular breaking, but you might if you're coming down a hill and your brakes fade, or lose them altogether because the fluid boiled due to excessive moisture in the lines. Or, you have a failure in somewhere in the system due to rusting caused by moisture - something I never thought of, until recently. This could be a pretty scary thing to have to worry about, especially if you often carry a load. (which I don't) On the other hand, my new BMW tells me I have to change every two years regardless of mileage. That seems like an overkill to me. Manufacturers seem to vary in their requirements, so one has to wonder. Is this really necessary, or is it just another reason to get you into the shop more often than necessary? I don't live in a humid climate, so it's probably an overkill. If you live in the South Pacific, I'm sure it's not. But this brake fluid moisture tester should help with this. As others have said, this tool is very easy to use, gives an instant reading, and should save a lot of hassle and unnecessary expense. My only complaint about the tool is the annoying upside-down orientation of the display. And, it shuts off when you pull it out of the fluid. Otherwise, it seems very well designed and built. The instant color coding reading is very helpful and instantaneous.

It seems to work. Tested a recently filled brake reservoir, tested good. Tested a brake reservoir filled five years ago, bad 3.5%

Love this little tester. Easy to use. Will test DOT 3, 4, and 5.1. Good to have for all is DIYers.

The brake fluid tester worked great on my cars. It showed about 1.2 green light. Displaying not needing to change brake fluid.

Love the fact it takes common cells instead of button cell batteries. Very user friendly due to the color coded thresholds. A must for newer vehicles that require frequent brake fluid changes. This way you aren't needlessly changing good fluid out based off of a mialage interval or being hosed by a stealership when it doesn't need to be done!