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Brake fluid flush - when is it necessary?

J

John McCabe

Junior Member
2016 Honda Accord. 25K miles.

Last time I went to the dealer for oil change, he was strongly insisting on brake fluid flush. I didn't do it. Later I opened the cap and looked at the brake fluid - but I can't tell whether it is too dark or not.

How often is it generally necessary for the brake fluid flush? Also, the dealer was asking $160 for it, which seems a bit high.
 
2000 F250, 250k miles, original brake fluid, original PS fluid, original coolant, twice a year old changes or 30k miles whichever comes second. So, never?
 
If you drive it like you stole it, or long steep downhill stretches, your brake temps rise and it becomes more important to minimize water % in the lines to avoid mushy brakes.

If you don't have those scenarios, many just wait until a hydraulic component fails, then flush the system at the completion of that work. Others insist that it needs done very frequently like every couple years but I've seen no evidence that this really matters except as above, if you are driving in severe conditions.

Middle ground take on it would be every 5 to 10 years or 100K mi, whichever comes first, or more often if you're the type to keep regularly opening the fluid reservoir to check it which lets more and more moisture in each time. 😉 You can do that, get a brake fluid water tester and keep opening it to take readings, then expect to change it more often.

Your vehicle is not yet old enough to have significant historical data about weakest links in the hydraulic system. If you find there is one, that would be justification to increase the fluid flush frequency.

For now if it isn't in your owners manual as required maintenance, you're off the hook for warranty purposes and the dealer is just looking to make an extra buck off of you. $160 for a dealership to do it, seems about right. Expect to pay the most for anything there, including precious Honda fluids.
 
Eh... Only vehicle I have that mandates a flush schedule is my bike... Every two years.

Cars? I do them every 50k or 5 years. My tow vehicle? Depends on how much I've been towing and how much I've heated up the brakes.

I bleed them myself which is all the dealer is going to do anyway. Takes about 1/2 hour with setup with a power bleeder. More if you have a friend work the pedal.

Best part is my wife's car was in for state inspection at the dealer. They gave her a "report card" on the car denoting that the brake fluid was old and off color and that the coolant was also "tested" as old. The irony was, I had just put on new rotors and pads and essentially flushed the brakes. I had also just replaced the thermostat and a hose which involved draining the coolant and replacing with new coolant. Pretty sure that they wouldn't have recommended those things to me as I am a man, but then again there are a lot more men these days that don't know shit about wrenching on vehicles.
 
John McCabe said:
Yeah, the owner's manual. It no longer has a maintenance schedule. It has this maintenance minder with different codes that come on at the display. Looking at those codes, there is no such code for brake fluid change at all. Here are the codes

http://owners.honda.com/vehicles/information/2016/Accord-Sedan/features/Maintenance-Minder-System
Click to expand...
Right on that pdf from your link is this:

"Independent of the Maintenance Minder information, replace the brake fluid every
3 years. :
 
Its smart to do it every time you change pads I think. That should be every couple of years for most people. Trouble with old fluid is you don't know how bad it is until you boil it under hard braking. Plus a lot of cheap fluid has some pretty bad wet boil points. If you're using something like super blue with a good wet boil point its probably not as important. Just one of those things that is 100% fine until its not and when its not, its an emergency situation typically.
 
Depends on the vehicle but I do it only when the fluid looks dirty. So every few years or so. I do it myself. The worst part if having to lift each corner to remove wheels. I hate removing wheels. Other than that; exchanging fluid while bleeding is super easy.
 
For the cars that I track, I keep the fluid <2 years old.

For DD cars I flush at every brake-related service, 3-5 years or so.

Brake fluid is quite hydroscopic, so if you live in a humid area it is more important to flush than in dry areas.

FWIW inspecting the reservoir is nearly useless because brake fluid doesn't circulate. You need to flush some out of a line or caliper for a meaningful inspection.
 
So as someone mentioned, those "precious" Honda fluids - I am assuming it does not matter whether the fluid is changed at the dealer or an auto place?
 
John McCabe said:
So as someone mentioned, those "precious" Honda fluids - I am assuming it does not matter whether the fluid is changed at the dealer or an auto place?
Click to expand...
Er, assuming its a good auto place, it's fine. I presume it'll be just any DOT 3 fluid, but the fluid type should be in your manual.
 
John McCabe said:
So as someone mentioned, those "precious" Honda fluids - I am assuming it does not matter whether the fluid is changed at the dealer or an auto place?
Click to expand...

Honda has some weird formulations on some of their fluids. I don't remember if brake is one of them, but so long as it meets the spec you're fine.
 
Brake fluid absorb moisture/water and water promote rust.

I once bleed a 30 year old car and there are rust pieces coming out with the brake fluid.

So, if you were only to keep the car for 5 years, don't change it. If you want to keep your car until the wheel fails off, change it every 5 years is good enough.
 
Last edited:
As many have said, the issue is the water content in the fluid. It will boil when hot and that creates steam which is incompressible and leads to rapidly fading brakes. My biggest concern as mentioned by HarriLui is that the fluid becomes corrosive. It any vehicle with ABS, you have some expensive, sensitive components that may end up failing if the fluid isn't changed. It really is an easy thing to do as a DYI for most non-hybrid vehicles with a power flusher or a second person to operate the brake pedal. Even at the dealer, it shouldn't be too expensive.

I replace mine every two years which is the most aggressive schedule I've encountered.
 
So people can get an idea of what impact moisture has on brake fluid performance.

dtgoodwin said:
As many have said, the issue is the water content in the fluid. It will boil when hot and that creates steam which is incompressible and leads to rapidly fading brakes. My biggest concern as mentioned by HarriLui is that the fluid becomes corrosive. It any vehicle with ABS, you have some expensive, sensitive components that may end up failing if the fluid isn't changed. It really is an easy thing to do as a DYI for most non-hybrid vehicles with a power flusher or a second person to operate the brake pedal. Even at the dealer, it shouldn't be too expensive.

I replace mine every two years which is the most aggressive schedule I've encountered.
Click to expand...

Um... steam is very much compressible. I assume a typo?
 
I bleed them every time I service the brakes. UNLESS its a hybird or a car that rarely gets driven then once every 3-5 years. Newer cars brake systems are more tighter than older cars so they seem to hold up better IMO.
 
When it looks like this:
VzIPx7W.png
 
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