How often do you REALLY flush your brakes?

[LarryM]

Flushing brakes is easily my least-favorite maintenance task, and is made even worse when it includes flushing the clutch hydraulics. I use a Motiv pressure bleeder but that doesn't make it any less of a chore. I just don't like working with brake fluid, period.

As we know, BMW recommends doing this annually which to me seems extreme. I've been doing it approximately every two years on both my E24 and E28, but even that seems like overkill on cars that live in a dry climate and are basically garage queens, driven only a few thousand miles/year in fair weather.

What kind of driving/environmental conditions is YOUR car exposed to, and do you actually adhere to an annual flush?

[kojo96]

Personally, I think more than a few of the annually recommended services are a waste of time and money. Especially on cars that aren't driven much.
Use quality products, invest in a decent brake fluid testes, when it reads bad flush the fluid.
I've had cars where fluid changes (except for oil) did not happen on a regular basis on cars that saw 30k+ annually. Never had an issue.

[topher800]

What kind of driving/environmental conditions is YOUR car exposed to, and do you actually adhere to an annual flush?

I have never changed brake fluid in between pad & rotor changes...on any vehicle. Can't believe I've ever changed pads in under 5 years, but maybe.

Our 2011 RAM 2500; the original factory pads, rotors and fluid were changed last year at 96k miles. 50% highway miles and 50% with a 3000lb camper in the back.

Colorado is dry, so I have assumed the hydroscopic issue is not as bad as coastal areas. The cars are used for general purpose, commuting, weekend warrior, some road trips, some spirited driving here and there. We do not accelerate into red traffic lights, just to slam on the brakes. No racing or track time.

[BMWCCA2]

In my 2002 days we would be required to change brake fluid within 30-days of completing tech for a track event, so it was done frequently with DOT3. I seem to recall a factory recommendation of 3-years. When I bought my Toyota pickup in 1984 I noticed there was no recommendation for ever changing the brake fluid. So, more as a science experiment than anything, I never did. At about the 26-year mark I had an issue and simply replaced the entire master-cylinder with reservoir and clutch master with a new parts from Rock Auto that cost about 130 bucks. Still have original calipers and hoses, and rear-wheel cylinders. I don't know if this is simply a credit to Japanese-made hydraulics, or the brake fluid used. I don't recommend this regimen for any BMW!

[duggi]

Every two years. And FWIW, I believe the BMW factory recommendation is every two years unless you face more extreme than normal environment or driving conditions on a regular basis.

[Mike W.]

I believe Derrick is right and it's an every two year recommendation. As to how often I do it, well, I have done it several times but rarely if ever every two.

I know it's probably about the boiling point, but to me it has another purpose. I've seen rust in master cylinders when they failed, I'm assuming from moisture absorbed from the air. As far as other manufacturers cars, some, like GM vehicles I've seen, have a big flexible rubber boot in the M/C reservoir so they're not vented to the atmosphere and shouldn't absorb moisture. Knowing how funky old fluid can look like I also make a point to push out the old fluid when doing pads rather than pushing it back into the M/C. So kind of a micro flush.

[BMWCCA2]

I believe that when our cars were new, the BMW recommendation was every two-years. That stayed the same until fairly recently when I believe it is currently considered necessary every three-years under the CBS (Condition Based Service). Of course three-years means you're likely to get only one change under the current new-car Maintenance program. When it was two-years the Maintenance Program was 4-years so they were on the hook for two brake-fluid changes. I doubt the change is based on science or experimentation. Most likely a financial decision.

[Mike W.]

I was wrong. I decided to look it up having a owners manual for an 85 E28 on the shelf and it says once a year.

[BMWCCA2]

I was wrong. I decided to look it up having a owners manual for an 85 E28 on the shelf and it says once a year.

That makes sense. I remember being compelled to do the change almost every time I turned around. No wonder! Of course that was back when we needed a valve adjustment, what, every 12,000 miles? Or was it less?

[Mike W.]

I was wrong. I decided to look it up having a owners manual for an 85 E28 on the shelf and it says once a year.

That makes sense. I remember being compelled to do the change almost every time I turned around. No wonder! Of course that was back when we needed a valve adjustment, what, every 12,000 miles? Or was it less?

Not to mention I couldn't get much over 5K out of points or plugs on my old Bavaria.

[bigwave]

On the higher end, I waited about 8 years before doing it this spring and not only did the bleeder screw need some serious love to get loose, but the brake fluid moisture tester was off the chart. It then felt so much better when I drove it next that my guilt got the better of me and I did it again this fall. This is a seriously overlooked maintenance item my many people.

I live in a colder climate and it is damp in our garage.

[John in VA]

There are brake fluid test strips & pen-shaped testers.

[dsmith]

Every 2 years I replace mine. I have a Mityvac, so it only takes about 30 minutes and a quart of fluid. I suck out the reservoir, refill and makes 2-3 rounds on the calipers around the car. No problem teaching the bleed screws, without lifting the car.

[topher800]

So this discussion made me go check the manuals of current vehicles and couple from the past. Stuff is all over the map.

2011 RAM 2500 - nothing listed
1998 Silverado - nothing listed (new silverado is every 75,000 miles)
2002 Passat - every 40,000 miles
2013 Audi - every 2 years; all models
1960 CJ3B - nothing listed, but I see I am supposed to repack the wheel bearings every 6,000 miles

[LarryM]

Bentley implies that bleeding the clutch along with the brakes is a "good idea" but not absolutely necessary.

Do you guys include flushing the clutch hydraulics as a standard part of the job? And if so, how do you go about it? Pressure bleeder or "reverse" bleeding from the bottom at the slave cylinder? Bleeding the clutch means having to get the car up in the air, thus making the whole job a little more involved.

[gadget73]

Not often enough, but I do own something with a goofy expensive brake system that really should be flushed every few years. My Mark VII has the Teves Mark 1 ABS rig, that getup with the hydac ball that relies on an electric motor for assist and rear brake pressure. Makes bleeding the rears easy, just need someone at the rear wheel to open the bleeder while the pedal is lightly applied. The electric motor does all the work. Only trick is not running it empty, otherwise its kind of annoying to get it to prime again. Front brakes bleed in the usual manner. A replacement ABS unit is about what the car is worth, and they get really crabby about nasty wet fluid.

I have occasionally cheated and just emptied out the reservoir and refilled with fresh juice. Doesn't do anything for whats in the line of course but I figure it has to be better than nothing. Done that with power steering fluid too.

[tschultz]

I started using ATE typ200 as it has a higher wet boiling point that other fluid's dry boiling point.

I did it once after a brake master failed on one of my cars. I found the fluid so dirty, I figured my other vehicles ought to be flushed too. It made a difference in feel in braking the first time I did it so I went ahead and flushed every car in my fleet. I started doing a full flush every 4-5 years (making sure the fluid runs clean).

An easy way to improve your braking system without spending much money. I bleed with a hose and a jar and do it as a single person job.

[a]

"An easy way to improve your braking system without spending much money. I bleed with a hose and a jar and do it as a single person job." I never got as good a pedal until I adopted this method. Gravity bleeds work great too, but is way too slow for a flush. Most of my experience with bleeding brakes comes from replacing rusted out lines; which gives you a clue about how often I flush brake lines

[austin8753]

admittedly, a lot less often than i should be doing it. i flushed the brakes on my M5 a few weeks back. the fluid had very little mileage, but the car had been off the road for close to 15 years and had absorbed quite a bit of moisture in that time - when the fluid came out, it was very milky looking. so, now, i will be making sure to do it every other year.

[BDKawey]

this is on my list for the daily, its never been done in the nearly 6 years, 100k miles ive owned it..

certain have exceeded anyone's interval haha

[duggi]

"An easy way to improve your braking system without spending much money. I bleed with a hose and a jar and do it as a single person job." I never got as good a pedal until I adopted this method. Gravity bleeds work great too, but is way too slow for a flush. Most of my experience with bleeding brakes comes from replacing rusted out lines; which gives you a clue about how often I flush brake lines

To be honest, I feel the same. I've had the chance to use a friend's pressure bleeder and was less-than satisfied with the process and results vs just doing it myself manually with a jar/hose and jumping in-and-out of the car to pump the brakes/fill/check.

I've been behind the wheel of a car (1973 Bavaria 3.0s) which had it's brakes fail while driving down a long grade at 50 mph and it was one of those "life flashing before your eyes" moments...so I'm extremely sensitive to any braking abnormalities now. I had to coast the thing into a 10-foot tall hedge while aggressively downshifting so I didn't slam into a bunch of traffic waiting at a light the bottom of the grade.

Lesson of that story is for me was to maintain my brakes better than anything else. I flush them every two years, period. Ever since that experience, generally the very first thing I say whenever I get in someone else's (or a used car) that's more than 3-4 years old is, "feels like your brake fluid needs changed," because people just simply don't do it enough or at all. And like others have said, fresh fluid keeps things clean...it's cheap insurance to ensure the longevity and reliability of the most critical safety system in your car.

[glowell222]

I flush the brakes every two years on all of the daily drivers. An unpleasant Saturday, but I feel it is worth it.

[LarryM]

I recently flushed my brakes and clutch hydraulics; it's been 2 years since I last did it and I've only driven the car about 500 miles during that time. I also live in a dry climate and the car is garaged full-time. Out of curiosity I purchased one of those pen-type brake fluid testers. The fluid I removed still registers 0% water content.

Regardless, there are some other factors to consider besides water contamination, so I'll probably continue to change it every couple of years. A Motiv pressure bleeder does make the job a bit more tolerable. It's getting under the car to bleed the clutch line that's a PIA IMO.

[garageboy]

When I was driving my E28 30,000 miles per year (working in MA) in the 1990s, and I was attending HPDEs with the car club, I definitely was bleeding my brakes every year or so. But I was also replacing brakes more frequently. Now that I drive about 10k/year, I do it every few years.

One thing I am certain of, that others here have mentioned, there is no question that the brakes perform noticeably better after I've bled AND flushed them, so I find myself laughing cynically at people that spend all kinds of money on various brake "upgrades" when they don't bother to maintain their fluid properly (no one here, of course, I mean, it's those wankers on Facebook ). Fluid absorbs water and dirt over time. It just does. I live in a relatively moist climate, but the car is garaged. Garaging a car is the single best thing you can do to preserve it.

So I think 3 years is the maximum I'm willing to wait between fluid changes.

[Mike W.]

One thing I am certain of, that others here have mentioned, there is no question that the brakes perform noticeably better after I've bled AND flushed them,

Really? That noticeable?

Garaging a car is the single best thing you can do to preserve it.

I can't argue with that, but... Not always easy even if it's technically possible.

[craigb93]

My cars probably fall into the 3-5 yr flush category.
That said, no one mentioned using DOT 4 LMA fluid (Low Moisture Absorption). The price is close to DOT3 just harder to find. When I find it I get 6-8 quarts. Not a question about shelf life if unopened. Atlanta is in the middle for moisture for me. The better shops in the area use the DOT4 as their 'standard'.
-Dick

[tn535i]

Cars that get driven regularly usually about 2 years, otherwise like my M6 or our e30 project maybe 3-5.

I use DOT 4 and I think it's LMA...
Laugh every time at those who waste money on the pressure bleeders
I first suction fluid from the reservoir and refill with clean so I don't send old down the lines
A hose into a jug works great, I like used washer fluid as they are sturdy
I stuff one end of the hose down into the handle so it stays put, add fluid from vacuum so it doesn't tip over
This will gravity bleed your brakes if you just open the bleed screw but I pump the pedal to hurry it along
Usually do this when rotating tires and it's 30 min extra work/time
Bang on the calipers with a hammer or heavy wrench to dislodge any air bubbles that might get stuck
Always ensure a dust cap goes back on
Usually no more than a few drop to clean up

I've been told here it's OK to recycle brake fluid with used oil so that's what I've done at times but recently saving the brake fluid in those washer fluid jugs. It should be recycled properly.

[adawil2002]

Every other year like clockwork. I do not do it myself, I let trusted shops do the fluid flush & the disposal fee is minimal. I'm happy to pay for the service.

[RetiredDoc]

Every time I replace the master and slave cylinders.

That means once in the past 35 years, at the 20 year mark. So, my next brake flush is due sometime around 2026.

[tn535i]

I've found that if I do them somewhat regularly I do NOT notice any improvement in the pedal. Whenever I have worked on a car that was really neglected I notice an immediate improvement in the way the pedal feels. Same for the clutch hydraulics.

Some of you may get by with NEVER bleeding your brakes and only touch them when you use the pedal to stop. I don't want my cars to develop a mushy pedal over time and potentially have fluid boil and loose pedal if I find myself in an extreme situation. So I bleed my brakes.