Brakes

[u/KAO7781]

My mechanic is telling me to change my brake fluid I only have 28,000 miles on my vehicle should it be changed? I have never in my lifetime ever changed brake fluid so I have no idea. Thanks, price is 149. He said Florida vehicles need changing sooner than any other states because of our wonderful tropical weather..

[u/503Automotive]

Good afternoon i am in Colorado normally a brake flush is done at 50,000 miles there just trying to take more money out of you

[u/DepletedPromethium]

its done via a process called bleeding.

you drain whats in the brake fluid resorvoir with a big plastic syringe, add fresh fluid to the max line and you use something like a pressure bleeding system that pressurises the resorvoir, and you crack open the bleed nipples on all 4 brake calipers/drums starting from the furthest away from the resorvoir, making your way to the closest, this way you're forcing out all the old fluid from the system and replacing it with nice new fluid, and bleeding it prevents air entering the system as air is compressable where as fluid is not compressable, air in brakes is bad and if your brake fluid is very old or very contaminated with moisture you can boil off the water content and it creates pockets, voids of air which is dangerous and reduces braking effeciency massively.

I got a pressure bleeding system that cost £32 and came with multiple resorvoir attachments to be universal out of the box, I modified it with a inline air regulator to keep pressure under 20psi as my pressure system connects to a spare tyre for "free" consistent pressure, and i added one way valves to the system and to the outlet i attach to each bleed nipple preventing any bubbles or old fluid making their way back through the system, total cost was about £50, a 1ltr bottle of dot 4 brake fluid is rather cheap, i buy Comma brand which is £7, my brake system has 1.1ltrs of fluid in it so 2 bottles are needed.

You're paying a mechanic more for their time than for anything else as the fluid is cheap and they use their own pressure bleeding system that most likely uses a compressor, or if they aren't as fancy they will have a pressure bleeding system that must be pumped up. (these are twice as expensive than the system i got, for a good quality one anyway)

brake fluid is hydroscopic, it absorbs moisture and this degrades the fluids performance, you can buy a really cheap brake fluid tester pen that you stick into the resorvoir and push a button and it reads the water moisture content.

generally you want to replace brake fluid every 2 years or after a certain milage depending on the vehicle, if you do a lot of heavy driving with lots of braking then its very recommended to change your brake fluid every year, I live in england which is pretty much 85-96% humidity 95% of the year, i've never had brake fluid become contaminated by moisture, it just degrades due to heavy driving as it pretty much boils in the system due to residual heat from the rotors radiating the calipers and pistons.

if you've owned the vehicle from brand new then you're overdue a brake fluid change, if you get it serviced by a mechanic every year then you should have invoices for work they have done, scan them for any mention of brake fluid or even master cylinder/abs pump work as anything like this requires a bleeding of the brakes, if you've had a caliper changed, or a drum in hat system replaced, it too will have came with a brake bleed but only for those affected wheels.

[u/wingman3091]

29,000 miles is low mileage for brake fluid - however, brake fluid is hydroscopic meaning it can absorb moisture from the air so if it's old it should be changed. I recently changed the factory fluid on my '06 when I replaced my brake lines, and at 180,000 I noticed the difference. The brake fluid was disgusting.