My tester just arrived and I tested my system. I just changed fluid in June so I didn't expect to get a failing result. Mine read <1%. Up to <2% is just by the tester manufacturer to be ok.
The device is very easy to use and appears to work correctly. It says it is calibrated for DOT4 so that implies some level of accuracy, but the package doesn't come with a spec sheet so we don't know the accuracy. It also appears to be German which also gives me some confidence.
It is important to take the reservoir screen out before starting. Install the battery in the device and push the button on top to ensure it's working. Take the bottom cap off and expose the probes. Push the button again and when the battery light illuminates, THEN insert it in the fluid and you will get a reading within a couple seconds.

I'll be checking it over time to see if the fluid degradation is captured by the device. This cost effective tester may help limit changes to only when needed and let people know if they need to change fluid earlier than the scheduled time.

ChuckJ

 

This is very interesting. Where exactly did you source the tool?

 

Purchased at Amazon for $21.95.

ChuckJ

 

Thanks! I'm gonna grab one. Can't have too many tools.

 

I do wonder if the reading for the reservoir will be the same as for the calipers as there isn't any circulation. It may be close enough as the moisture may migrate.

ChuckJ

 

That's an interesting question, ie, the homogeneity of moisture level throughout the hydraulic system. One way to check would be to get a meter reading on the first fluid out of the caliper during a flush and compare to the reading at the reservoir. Anyway, I've ordered the tester. Thanks!

Spyder

 

Yep, good idea! If you show <1 or 2% at the reservoir the difference in reading might not be critical, but as you get toward the margin it might be.

ChuckJ

 

read some of the reviews on Amazon ....most seem satisfied with this Taiwanese product which comes with no known manufacturer or documentation of accuracy , but a few tested it on brand new unopened bottles of DOT 4 and got " red" readings, so one wonders what the specificity of this device is..if it is only 80% ....hmmmm
no one knows , so YMMV
I prefer to just change fluid every two years on all my cars irrespective of miles , since I don't track any of them and none ever see more than 8k miles put on annually and flushes are relatively cheap

 

There is a sequence (which I outlined above) and if you don't follow it, you do get incorrect readings.

ChuckJ