How often do you need to change brake fluid?

Maintaining equipment will help it last longer. Changing brake fluid is maintenance for the brake system.

You are overdue. Suggest doing it now.

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Some people will use brake fluid testers for moisture content, or test strips for dissolved copper content, as a guide for how soon to fuss with the fluid.

 

or

 

it may depend on climate somewhat. i haven't changed mine yet, consider it an experiment.

 

When you look at the jug with a flashlight stuck up against it is the brake fluid almost clear a very light yellowish brownish color and I mean very light. What I did on the '09 when I first got it was pull all the brake fluid out of the reservoir it looked good. But I did it anyway pull all the fluid out of the reservoir I filled it with dot five which is what I use in all my power sports equipment. Yeah yeah it's not rated for this car but so be it. And then all I did was go crack each zerk fitting like I was bleeding the brakes and just let it run till it ran and the color changed on the napkin then close go to the next. And I pulled the relays to do the fronts or the backs whichever the instruction said I can't remember and it seemed to work great The fluid in the reservoir didn't really change color but I know it's my Motul dot 5.

 

You absolutely amaze me, almost every time you post. Is there anything you haven't jerry rigged or done halfassed?

 

Not half-assed at all didn't have to take it all apart push the old fluid out and with the new half nice person I guess seem to be the logical way to do it to me the brake fluid motul . Will last so long it's crazy .

 

Had my car 14 years about 170,000 miles when I sold it rotors looked good braked fine original fluid. Not proud of it but brakes on a Prius have a very easy life. If there not complaining leave them alone.

And I sure wouldn’t let the dealer at them ouch that will hurt..,,.mine is at $175 an hour last I looked pre Covid.

 

currently still have original brake fluid. 06 and 98k miles. brakes are super brakes and responsive in traffic

 

That's your choice. Ya pays your money (or not) and takes your chances. Maybe everything's "fine" for as long as you own the car. Maybe that pump starts running a bit more often?

All I know is the few times I have had to replace failed ABS hydraulic actuators, they had old crappy fluid in them. Coincidence?


This is one ABS unit on a Honda that I did an "autopsy" on by breaking some of the valves off to see what I could.A valve was leaking causing a sinking brake pedal. Flushing the fluid didn't help. Can you tell which of the 4 was bad? (Hint, it doesn't look like the other 3)

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I used to never think twice about brake fluid until on another twelve or so year old car which had 150k miles on it with original brake fluid developed corrosion on the brake lines which were expensive to replace. Since then, I change mine every five years. Cheap insurance.

 

Following some experiments I did with fresh brake fluid and brake actuators, I'm now a firm believer in brake fluid upkeep. A few dollars of brake fluid vs a couple thousand for possible actuator replacement? I'll keep up with the brake fluid just for the chance it prevents the other.

 

To baste fluid out of reservoir most anything will do. On my gen 3 I used a large syringe with tube extension. And for the bleeding, pushed a bleed valve coupler (the only part of my Mighty Vac kit I used, lol) pushed into clear tubing, run to a Kirkland Mayo Jar through a hole drilled in its lid. Also had assistance pushing the brake pedal.

For Gen 2 the Repair Manual doesn’t detail a non-Techstream method. Attached is the Techstream procedure.

Dealerships should be capable and amenable to do this, for under $150, fwiw.

there’s a link in my signature for brake fluid replacement tips, albeit third gen. (On a phone, turn it landscape to see signatures).

 

That's a pretty close description of older, conventional brake systems. It's a little different in a Prius.

The four lines to the wheels are still dead ends. That fluid can sit there and get old, and get old and hot inside the wheel cylinders.

Up at the head end of the system, it's different; that fluid is getting continually pumped from the reservoir into the accumulator, running through the actuator valves, and ultimately circulating back to the reservoir as you use the brakes. So what's in the reservoir is a pretty good representation of what's in those head-end components.

It's not hard to go crack a bleeder at a wheel and get a ml or so of the old stuff out and dunk a test strip in it, if you want to check that as well as what's up front.