Why does nobody talk about how bad cheap brake fluid can get?

I was flushing the system on a 2010 Civic yesterday and decided to test the old fluid that came out with a cheap moisture meter I got off Amazon for like 15 bucks. The reading showed it was over 4% water content which is basically dangerous territory for boiling under hard braking. I knew old fluid could be bad but I didn't realize it gets that contaminated that fast even in a daily driver that never sees a track. Found a study from a brake parts manufacturer saying most cars on the road have fluid that's 2-3 years past its safe lifespan. Made me wonder how many of us are just topping off instead of actually testing the fluid's boiling point. Has anyone else ever checked their own car's fluid and been shocked by the results?

3 comments

3 Comments

pat_harris17d ago

My neighbor's been a mechanic for 30 years and he says this moisture meter stuff is mostly hype for daily drivers. He showed me a sealed master cylinder from a 2008 Camry with 150k miles that still read under 2% water when he tested it. Sure, track guys need to worry, but topping off every year or two probably covers 95% of us just fine.

abby_fisher17d ago

Used to be one of those people who flushed brake fluid every two years like clockwork. Then my buddy @pat_harris showed me the same test on his mom's old Accord, and it barely registered above 1% after a decade. Definitely changed my mind about how urgent the whole thing is for normal cars.

blairm7717d ago

Doesn't the real issue come down to air getting into the system from old seals and gaskets though? Even if the fluid stays dry, rubber parts wear out and can let moisture in through the reservoir cap over time. That 2% reading might hold up in a sealed master cylinder, but how many daily drivers have factory fresh seals after 10+ years of heat cycles?

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