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View Full Version : How often do you change brake fluid in your car?



ken masoumi
05-06-2015, 10:23 AM
I just took my Civic(70.000 mile on the odometer) to the local mechanic to change the front pads and possibly the rotors, the car has never had a brake service done since I bought it new in 2007,I asked the mechanic if he's going to change the brake fluid he said they usually don't "if it's not needed" ,Honda recommends every 3 years or 30.000 miles, some believe the brake fluid does not need to be changed since it is a "sealed system" ,I can't be sure it is as sealed as they claim it to be.
How often do you change your brake fluid?

Chris Padilla
05-06-2015, 10:40 AM
The intervals I hear the most often is every 2 years so that is what I do when I change mine.

Robert Engel
05-06-2015, 10:47 AM
I've never done it. My mechanic (who's never steered me wrong so far) says its optional.
Maybe that's wrong, but I've owned alot of vehicles in the last 40+ years.
I;ve had trucks with up over 300,000 mi. on them and never had an issue.

BTW, same thing with transmission fluid. The only time I changed it I within a day or two I had trouble with it.
Now, I never change it either.

Ken Fitzgerald
05-06-2015, 11:01 AM
I change mine every 3 years. I live in a mountainous area where brakes are important.

Howard Garner
05-06-2015, 11:08 AM
My manual says every 2 years, I have averaged every 3 years or so.

Howard Garner

Greg R Bradley
05-06-2015, 11:12 AM
I'd be skeptical of it being a "sealed system". There are some reservoirs that have a rubber diaphragm between the vented top portion and the fluid. Possible, but not likely on your Honda. IF he is wrong about that then ?????

Conventional brake fluid is hydroscopic and pulls moisture from the air. If you are in a warm/moist climate I would change every two years as the moisture gets IN everywhere and the hydroscopic fluid is absorbing the moisture that gets in through the vent hole in the cap. I'm in dry SoCal and always did that every 3-4 and checked the system for moisture as I was doing it. Any COMPETENT mechanic should have a supply of moisture test strips.

Later systems are more likely to use fluids that are not hydroscopic. The fluid in my 1991 Jaguar was still passing moisture test after 20 years but that fluid is not cheap.

Sometimes you want to change it just to flush fresh fluid through the system so that you can see any discoloration in the fluid coming out, which could tell you the condition of the flexible brake lines and seals.

Bottom line is there is no standard answer.

Ken Fitzgerald
05-06-2015, 11:19 AM
It depends on the type of fluid used in your system but non-silicon brake fluids are hygroscopic. They absorb moisture from the air. The water vapor absorbed reduces the temperature at which the brake fluid will boil and turn to a vapor. Vapor in your brake lines/system can lead to brake failure.

The area where I live is relatively arid so though it's recommended to change it every 2 years, I go 3 years but I do change it.

Malcolm Schweizer
05-06-2015, 11:33 AM
I would say two years, but it also depends on the car, the climate, and the driving conditions. On my 1972 VW I would change it very frequently. Okay, actually it would sometimes change itself, but that's another story. On my Jeep Liberty I shoot for 2 years, but sooner if it is brown looking. We have very steep roads, so the brakes get a lot of wear and tear. Also we are in a humid environment, and condensation can build up in the lines.

Even though it's a "sealed system," condensation still gets in, and also the fluid breaks down in the high heat generated during braking. As it breaks down or as water builds up in the system, the fluid becomes more compressable, and therefore the brakes get mushy.

If you have ABS, then you need to have a mechanic bleed it unless you have a pressure bleeder. You can really mess things up otherwise. There is a diaphragm in ABS systems that has to be pressure bled or else it deforms. Also the OBDII fault codes may need to be reset if you don't have a code reader.

Pat Barry
05-06-2015, 12:21 PM
I have never changed the brake fluid, only topped it off after bleeding as part of a caliper rebuild

ken masoumi
05-06-2015, 12:30 PM
I just got my car back, the mechanic said the fluid was "fine" so he did not change it, just topped it up after replacing the front brake pads,I must add he is recommended by a few neighbours who described him as a trustworthy no nonsense mechanic.

Chris Parks
05-06-2015, 12:36 PM
And I would ask him how he knew it was fine. He may be correct and the car might have silicone fluid but all the same I would want to know how he concluded it was fine.

Myk Rian
05-06-2015, 12:38 PM
I've never done it. My mechanic (who's never steered me wrong so far) says its optional.
Maybe that's wrong, but I've owned alot of vehicles in the last 40+ years.
I;ve had trucks with up over 300,000 mi. on them and never had an issue.

BTW, same thing with transmission fluid. The only time I changed it I within a day or two I had trouble with it.
Now, I never change it either.
+1 and +1
Have never changed either.

Mel Fulks
05-06-2015, 1:21 PM
Agree with Chris. It could look "fine",can he see if it has taken on moisture? There are warnings on brake fluid cans to put
the top back on immediately. I've seen guys checking fluid leave top off resovoir while they go find more fluid to top off.

daryl moses
05-06-2015, 1:44 PM
I usually just trade.......

Rick Potter
05-06-2015, 2:10 PM
I had a Ford pickup, back when anti lock brakes were just becoming common. As has been said, brake fluid is hydroscopic, absorbing moisture. The brakes worked fine after it had some mileage on it, but the anti lock light stayed on.

The anti lock valve that operated the system had gotten rust inside and quit working, which made the truck revert to a default system of normal, non anti lock braking. It cost $1,000 to fix.

I have no idea if the newer systems are better guarded or not.

Matt Day
05-06-2015, 2:20 PM
The only reason I'd change it would be if the pedal felt mushy and or travelled too far before doing anything. That's a sign there is water or air in the line and you need them bled. My opinion is based on about 15 years of working on mountain bike disc brakes (same basic design,
same principle, smaller size).

Art Mann
05-06-2015, 3:33 PM
I spent most of a career working as an engineer for a major automobile company. I am aware of what goes into creating a recommended service schedule. It is not done by tech writers. It is done by expert automotive engineers who know what they are doing. I would trust the schedule in the owner's manual.

Chuck Wintle
05-06-2015, 3:35 PM
I just took my Civic(70.000 mile on the odometer) to the local mechanic to change the front pads and possibly the rotors, the car has never had a brake service done since I bought it new in 2007,I asked the mechanic if he's going to change the brake fluid he said they usually don't "if it's not needed" ,Honda recommends every 3 years or 30.000 miles, some believe the brake fluid does not need to be changed since it is a "sealed system" ,I can't be sure it is as sealed as they claim it to be.
How often do you change your brake fluid?
on my Honda Civic the brake fluid was never changed in 16 years. Brakes never failed although once a brake line rusted out and fluid was added to bring up the level. The system is sealed so no moisture should be able to get in. YMMV.

Dan Hintz
05-06-2015, 8:31 PM
Just for clarification, the term is hygroscopic, not hydroscopic. Along with the reasons presented earlier for changing the fluid every few years (pedal mushiness, etc.), one of the big problems with water in the fluid is the damage done to the brake system itself. The pistons will begin to rust/pit, and the calipers will fill with sludge... this leads to frozen calipers, which will quickly eat pads/rotors and require a rebuild of the calipers. Not cheap, and not fun.

Brian Henderson
05-06-2015, 9:41 PM
I've never flushed the entire system, but every time I change the brake pads, I syphon out a lot of the fluid to keep it from overflowing and I replace it with new. Otherwise, other than verifying that it's full, I don't worry about it much.

Dan Hintz
05-07-2015, 6:15 AM
I've never flushed the entire system, but every time I change the brake pads, I syphon out a lot of the fluid to keep it from overflowing and I replace it with new. Otherwise, other than verifying that it's full, I don't worry about it much.

That leaves the dirtiest stuff in the calipers...

Justin Ludwig
05-07-2015, 6:37 AM
Out of all the vehicles I've owned, I've only changed brake fluid once - because I replaced the master cylinder on a 92 chevy. My first car was an '87 Civic - never changed the brake fluid in that one and I sold it in '96.


If you can't sleep at night, change the fluid or pay your mechanic another $$$ to do it.

Jim Matthews
05-07-2015, 6:46 AM
Most of my driving involves an elevation change from Sea Level to +40 feet
and back again. I doubt the brake fluid ever gets above 150 degrees.

These are simple hydraulic systems with few moving parts.
Why treat something with no symptoms?

roger wiegand
05-07-2015, 7:56 AM
Every 50 years, whether it needs it or not.

Actually, in probably a million miles of driving I've only once changed it on purpose, but I'm sure it has gotten swapped out as master or wheel cylinders were changed. I did do a total flush and replacement on my '50 Chevy pickup after only 40 years, as the fluid was brown with visible precipitate in it. Also replaced brake lines, master cylinder and rebuilt all the wheel cylinders at the same time, so that may not count.

Brian W Smith
05-07-2015, 8:06 AM
Every two years,same with clutch fluid on our cars/trucks.These having mid level performance brake setups(Dot 4 dino).It's once a year on the M/C's,with much higher end systems(Dot 5 dino).It's pretty quick,usually taking about as long to jack up/remove wheel as to actually bleeding.Get a vacuum bleeder.

Pat Barry
05-07-2015, 8:17 AM
I see the more recent Chevy manuals recommend changing every 72000 miles but the older ones basically said nothing about it. I suspect they changed to avoid lawsuits from some ambulance chasers

Harold Burrell
05-07-2015, 9:27 AM
I will preface this by stating something first...

I am in no way a mechanic. Yes, I do work on my own vehicles...but only because I am too cheap to pay someone else to do it. I have been "Shade-treeing" it for over 30 yrs.

OK...that said...I have never changed my brake fluid. Ever. And I have owned a lot of cars.

John Lanciani
05-07-2015, 10:29 AM
These are simple hydraulic systems with few moving parts...

I don't consider the antilock brake system in a modern car simple (and a new pump assembly is anything but cheap). Additionally, the brake system is used in conjuction with the traction and stability control systems and the increasingly common collision avoidance systems in new cars. Probably a pretty good idea to follow the manufacturers guidelines.

ken masoumi
05-07-2015, 10:39 AM
And I would ask him how he knew it was fine. He may be correct and the car might have silicone fluid but all the same I would want to know how he concluded it was fine.


Agree with Chris. It could look "fine",can he see if it has taken on moisture? There are warnings on brake fluid cans to put
the top back on immediately. I've seen guys checking fluid leave top off resovoir while they go find more fluid to top off.

The way he explained it I assume he is in the " sealed system /not necessary to replace" camp whether the fluid is Silicon based or not didn't seem to matter to him, after reading some of the responses here, it looks like he is not alone in that opinion.
I will find out in a few years whether he was right or not:).
Thank you all for sharing your thoughts.

Brian Henderson
05-07-2015, 11:49 AM
That leaves the dirtiest stuff in the calipers...

Not really because you have to squeeze the calipers dry to install new brake pads. If you empty the reservoir before you compress the piston, then do it again afterwards, you'll get most of the fluid in the system, with whatever is left in the lines remaining. Refill with fresh from a sealed bottle and you're good.

Rod Sheridan
05-07-2015, 12:25 PM
Every 3 years, same for my motorcycles.............Rod.

Greg R Bradley
05-07-2015, 9:20 PM
They try to call most modern brake systems "sealed" but that only means they are less open to the air than most older ones.

Virtually none sealed as well as many American integral reservoir cylinders from the 1970s that had a diaphram sealing between the top of the resorvoir and a metal cap that was held down by a spring clip. This allowed the air to come in the top so fluid could go from the reservoir into the cylinder but the air could not get to the fluid.

I can almost guarantee your Honda is NOT sealed in the complete meaning. My 2006 Honda Ridgeline has an O-ring in the cap and is called sealed but moisture gets to the fluid. If it didn't the fluid won't flow into the cylinder as the pads & rotors wear. Sure enough, it flunked the moisture test around 4-5 years in fairly dry SoCal. It flunked it again last year.

Fluid is cheap and brake parts are not. That doesn't even consider the safety issue.

Dan Hintz
05-08-2015, 6:24 AM
Not really because you have to squeeze the calipers dry to install new brake pads. If you empty the reservoir before you compress the piston, then do it again afterwards, you'll get most of the fluid in the system, with whatever is left in the lines remaining. Refill with fresh from a sealed bottle and you're good.

There is a LOT of fluid in the lines themselves... squeezing the calipers only sends (most) of your gunked up fluid into the lines, awaiting for a fresh batch to push the gunk back into the calipers. Not to mention if any of this stuff makes it back up into the ABS unit while compressing the piston, you'll quite likely be looking for a new ABS unit.

But hey, I don't like taking chances on stuff like this... others obviously don't mind.

Curt Harms
05-08-2015, 8:34 AM
I had a Ford pickup, back when anti lock brakes were just becoming common. As has been said, brake fluid is hydroscopic, absorbing moisture. The brakes worked fine after it had some mileage on it, but the anti lock light stayed on.

The anti lock valve that operated the system had gotten rust inside and quit working, which made the truck revert to a default system of normal, non anti lock braking. It cost $1,000 to fix.

I have no idea if the newer systems are better guarded or not.

That's the issue I'm aware of though we haven't experienced it. The repair quote I saw was quite a bit more than what you paid.

Jason Roehl
05-08-2015, 9:19 AM
I will preface this by stating something first...

I am in no way a mechanic. Yes, I do work on my own vehicles...but only because I am too cheap to pay someone else to do it. I have been "Shade-treeing" it for over 30 yrs.

OK...that said...I have never changed my brake fluid. Ever. And I have owned a lot of cars.

Same story here. I've never had a brake problem (on my own vehicles) due to brake fluid, after multiple pad/rotor jobs, changed wheel cylinders and the like--they were just worn out parts.

I did work on a church bus ('78, I think, Ford B700 with a 390 V-8) that had sat for 8 years. The brake "fluid" was barely a fluid. Just black sludge. I won't tell the whole story that goes with that bus here...we'll just call it a miracle bus, as there are 29 of us who probably shouldn't be alive...

Jim Andrew
05-12-2015, 9:50 PM
I never thought about changing brake fluid, till I was listening to a show on radio. Think it was Bobby Lykis. He said brake fluid will work ok at 50% water to fluid. Also, they started selling dot 3 synthetic brake fluid at Walmart. Now I only buy the synthetic as it does not absorb water.

Mel Fulks
05-12-2015, 10:04 PM
50 percent water. Well, I guess you could pee in the resovoir if stranded and needed brake fluid. Unless he is a comedian
I can't imagine why he would make such a statement.

Leo Graywacz
05-12-2015, 11:37 PM
Bought my current truck new. Now it's 8 years old. 73K miles on the odometer with the original brake pads. Never changed the fluid. Probably has the newer silicone fluid in it, not sure. Brakes work fine.

Jim Andrew
05-15-2015, 8:16 AM
The point he was making was that, although with half water your brake system will work, but the water will destroy your brake system. And if you look at the fluid,mixed half with water, it looks like brake fluid.

Mel Fulks
05-15-2015, 9:08 AM
Jim ,thanks for explaining that. Makes sense now.

Larry Edgerton
05-16-2015, 1:38 PM
I buy a new truck every two years.

So about every two years............

Mark Blatter
05-27-2015, 10:55 AM
I've never flushed the entire system, but every time I change the brake pads, I syphon out a lot of the fluid to keep it from overflowing and I replace it with new. Otherwise, other than verifying that it's full, I don't worry about it much.

A good friend, who was also our fleet director over 135 vehicles, also told me to do this same thing. After about 80K miles or so, use a basting bulb and pull out all the fluid in the reservoir each week for a few weeks. Do this every year or so and you will 'change' the fluid over time.

ken masoumi
05-27-2015, 3:18 PM
A good friend, who was also our fleet director over 135 vehicles, also told me to do this same thing. After about 80K miles or so, use a basting bulb and pull out all the fluid in the reservoir each week for a few weeks. Do this every year or so and you will 'change' the fluid over time.
I used to use a basting bulb to empty/replenish the power steering fluid when I had Chrysler but never thought the same method could be used for brake fluid.

Roy Harding
05-27-2015, 3:34 PM
You're supposed to change brake fluid?

Chuck Wintle
05-27-2015, 3:45 PM
can silicone fluid be mixed with regular brake fluid?

Ole Anderson
05-27-2015, 11:45 PM
You're supposed to change brake fluid?

Duh, yea, along with your flux capacitor at 100k miles.;)