Is this really necessary?

What kind of vehicle and use case?

I do it religiously on my motorcycles every two years, or after a track day. I still do it on cars and trucks, but I'm not as strict.

2019 Toyota Highlander with 30k miles

Thanks

Probably more critical in a high performance vehicle or in an environment that really stresses the system (e.g. mountains). I'm more inclined to frequently change the fluid in my Miata than in my CX-30.

Your miles aren't really an issue, IMO, but the vehicle age is. For me, it's a "while you're in there" item when you're replacing pads and rotors.

But I'm just a shade tree mechanic.

I have done it several times on DD cars/SUVs. I use a cheap HF hand pump system.

Start at the farthest from the resevoir and connect it. Fill the reservoir with fresh, new material and pump until it comes out clean. Last time I did it, it was coming out green instead of clear(ish).

Then move to the next farthest one (IIRC, Driver Rear, then Passenger Rear, then Passenger Front, Driver Front), pull material and ensure resevoir is full. Once last one done, you've flushed the system out and replaced all the material.

By hand took a minute, but easy to do. Keep a box wrench on the fitting to screw/unscrew it. Dump old stuff in container to throw away.

~egon

I don't think I have ever intentionally changed brake fluid or differential fluid. It's always been over the course of some other service like pinion bearings or caliper replacement. I might have done it once in 450,000 miles on my 2002 F150 when I changed a caliper but probably not.

I think it's a good idea to replace the fluid when it gets dark. Either way, the fluid looks like used motor oil and the truck still stops so....it should be done but I don't think it's a critical thing.

Since I flush and bleed brake fluid on my track car before every track weekend, I've gotten to the point that I flush and bleed my regular vehicles every time I change the pads. It is usually not even dark at that point, but since I have a pneumatic vacuum pump it is quick and easy and just seems like standard operating procedures for me now. Prior to taking up track driving I never flushed and only bled them if things got mushy.

I use siphon and replace. Suck put what's in the reservoir and put in new. Depends on the age of the vehicle. Maybe every 20k miles or so

So what's the right interval? Every 2 years, 3 years, when brakes are mushy?

Southside AG said:

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So what's the right interval? Every 2 years, 3 years, when brakes are mushy?

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When it's dark. It's clear when new. It's hydroscopic, so it's designed to absorb and hold that moisture and not let it just hang out Willy Nilly In your brake system.

When I have replaced it in classic trucks prior to fixing them up, I suck out the fluid from the reservoir and put fresh in it and then I bleed it through the lines until it comes out clear.

sts7049 said:

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it's 7ish years old. fluid can still degrade and absorb moisture. I would replace

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This.

But a tester or test strips.

Ever two years for me, especially since I live and spend much of my time on the Texas coast. Brake fluid is hygroscopic meaning it absorbs moisture through the air. I drive my vehicles for a long time so I want to keep any corrosion out of the brake system. If you live in a drier climate, three years may be ok but every two has worked well for me owning vehicles since the '80s.

An extended warranty may require you to follow the recommended maintenance schedule or it is void. My F150 maintenance schedule says replace brake fluid every 3 years and has a footnote saying fluid replacement requires special dealer equipment

The special equipment is to cycle the ABS module so that all the fluid is flushed and bled, but the module doesn't hold enough to worry about getting the very last drop out of it. If you don't have a mushy pedal you can skip the ABS module and the required computer tool.

Soooo, I'm guessing I should probably get the fluid changed in my 14 year old garage queen?