Brake and clutch fluid moisture tester

[Rich]

I'm looking for advice about an auto diagnostic tool that's new to me.

Most of us bleed the brake and clutch hydraulics every 2-3 years to make sure the fluid doesn't absorb so much moisture it starts corroding components.

Does anybody have experience using a brake fluid test tool like this one or this one to measure the fluid moisture concentration on their D or any other car? If the reading is correct for all of the fluid in each system and if the 2-3%(?) max limit is is correct then an owner would get a better idea about when to flush-fill each system rather than doing it by the calendar.

Some of these testers run $12-35 at auto part stores and online. Snap-On doesn't show them in stock. MATCO does. At $65.

Any folks out there who use such a tester and can share a recommendation?

I'll keep bleeding fluid by the calendar until I trust a better method/tool. A long trail of false test readings would be expensive.

[Bitsyncmaster]

It would be interesting to see how fast fluid absorbs moisture. Our reservoirs have an air bleed hole so not sure how fast that small hole affects moisture. I would think after a long drive the fluid gets hot so when it cools it sucks air into the reservoir.