Brake Fluid moisture tester
 

Has anyone ever used one of these? Are they accurate? Waste of time?

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might be a neat tool but all brake fluid will absorb some moisture and suck up some dirt. i myself always look at the fluid and if its dark i just replace it with new. it never hurts to keep your fluid clean.

I have that exact model, used it last week on my 2 year old DOT4........showed green and fluid did not look dark. EZ to use.

Not sure you really need one.Brake fluid changes color as it absorbs moisture. When its not clear, change it.:shrug:

Agree with above.Unless it's colored,most BF's ( and clutch)look like ginger ale when clean.

\db2

How are you going to test the moisture at the calipers? The brake fluid won't be consistent from reservoir down to calipers. It doesn't circulate and mix.

I have one. Some of the track day tech forms I sign off on want a moisture % number written on the form.

Yep, it measures resistance and probably fairly accurate. I saw one on Amazon for $10 and then the same one from China (where no doubt the one on Amazon was from) for ~$2 free shipping on eBay. Ordered for fun as I thought I would check the fluid as I did the Ranger Method for clutch fluid.

These are the results:
https://cimg6.ibsrv.net/gimg/www.cor...60b525a4db.jpg

My first drain fluid showed 3% moisture. At 4% requires changing. On the 7th drain it was zero, the same as the new fluid in the container!

Brake fluid is very hygroscopic (picks up water like a sponge!) That moisture will diffuse though the fluid from calipers to reservoir and will NOT be significantly different!

SIDEBAR
The product I received was in an obviously designed for US in a sealed blister pack. All US English no other language. Probably excess from a lot made for a US supplier who paid $1 and sells for $10! The Chinese give free mailing as a way to increase exports! Real fair completion! For me to ship a small item to China in a small Priority Mail Box it cost $35! Crazy.

Yeah my brake fluid after two and a half years and 10k miles showed <1% but the clutch was 4%. I flushed brakes today and had to get a turkey baster today to do the clutch later this evening.

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Oh, and I also used it to check a can of brake fluid that I had opened some time back to see if it was ok. It measured zero so I figured it should have been fine.

It looks like color is directly correlated.

Color is NOT a good indicator! You can buy test strips but these meters are cheap and work. Frankly I do the Ranger Method once a year so no need to measure as I do it whatever! I bought the meter because it was so cheap (just checked eBay and saw several for $2.99 free shipping from China!) I wanted to perform those tests when I did the Ranger Method!

GM says the color in the clutch fluid (DOT 4 brake fluid) comes from staining by the seals cause it to turn black quickly (I assume the graphite -or whatever- seals on the throughout bearing. Brake fluid dissolves paint so assume it will pick-up other "stuff" as well.) My color change is from draining the old fluid, putting in new and pumping the clutch 30 times. Repeat that ~7 times. Uses most of the 12 once containers I buy. Like to start with a new container ($4) where there is an unbroken aluminum foil seal on the new container.

I change my brake fluid yearly from tracking and the remainder of the bottle goes to the clutch so i was just curious too.

NJMP now tests water content in your brake fluid. Not sure which tool they use but I will find out on the 24th.

The problem with using a brake fluid tester is it might work better if it is calibrated for the type of brake fluid (DOT3 or DOT4) you are using to get proper results. Here is a DOT4 calibrated unit on Amazon:

Here is a tester supposedly calibrated for both DOT3 and 4:

You pay your money and take your chances.

Bill