My local friendly Skoda dealer has just asked me to book in for the last service of the 3 year warranty period.  When explaining what is covered he said a brake fluid change is not automatically included but is recommended and can be done for an extra £54.  When I asked why after only 3 years, he said its because the fluid absorbs moisture.

That got me wondering and I'd be curious to hear you guys opinions.

As far as I can see, the only way water can get into the system is through a vent not much bigger than a pin hole in the master cylinder cap.

Is enough water to worry about really going to get in there?

If any does, is it going to mix evenly with the brake fluid, or sink to the bottom and work its way down the pipes to the brakes and cause rusting to the cylinders and pistons?

Thanks for your views

Stewart

 

Brake Fluid is hygroscopic and can get H2o content and water boils / brake fluid overheats, 

So the manufacturers guidelines are now first change at 3 years and every 2 years.

It was at 2 years then every 2 not many years back.

 

It is called preventive servicing and maintenance.  Up to you if you bother, or get the Brake Fluid H2o content tested.

 

If you care to read up on the subject that is easy as mechanics / techs and others get trained on such things and it is not just Upselling.

Systems are vented, and there are weather and environmental conditions world wide that manufacturers need to consider. 

 

They do not know where you keep your car, drive it, or how you you look after it, so they make recommendations from knowledge and experience.

Just had mine done at three years old - £54.

 

Agree with everything George has said.  I wouldn't miss a brake fluid change interval.

 

Gaz

Edited 4 August, 20187 yr by V6TDI
typo

Water is also absorbed from around the exposed and moving parts of the slave cylinders which are sometimes immersed in water or road spray. 

If you have never experienced brake fade from overheating brake systems, you don't know what you are missing.

 

Its worth a £50 donation to the dealership to prevent that arse clenching moment you experience as the rate of deceleration you are used to and now require on that occasional significant hilly descent is delayed and then the subsequent realisation of it never arriving hits home. Worse still if you are a descending brake dragger....

As it is with OEM Brake Fluid from the VW Group you will want to replace that for track use, 

but even for spirited / sporting drivers that are heavy brake users, remember the XDS / XDS+ disables it's self when the brake system overheats and that is easily done with new cars let alone ones with standard discs, pads and brake fluids, and especially old OEM brake fluid.

Why is it three years and then every two rather than just every three years?

 

I would think the proportion of cars having this done after 5+ years will be quite small anyway I guess.

A clean brand- new braking system will have the best possible seal against the outside world and should be totally dry. As seals and pistons wear , and are contaminated by road dirt and ambient water, then the rate of contamination increases.

Just  an assessment off the top of my head.  

Any car that is serviced properly will have the brake fluid changed every two years. It may be true that many older cars are not fully serviced.

I had the fluid changed every two years in my Mk2 Octavia while I still owned it.

As said above , once you have had brake fade you do not want to repeat the experience. 

Austin Maxi coming down from the Cat and Fiddle into Macclesfield....... brake fluid was never part of the service schedule in those days.

Edited 4 August, 20187 yr by gregoir

9 minutes ago, juan27 said:

I would think the proportion of cars having this done after 5+ years will be quite small anyway I guess.

 

Guilty 

 

I rarely changed brake fluid, until c.2003 when I first discovered proper brake fade, at the exact moment you really don't want it.  Having then done a fluid change, the before and after braking efficiency was stark, and very noticeable.  It's too easy to become apathetic and not worry about it.  It's now something I'll do, or have done, to schedule.

 

With regard to how it gets in, don't forget the level in the brake fluid reservoir is going up and down, even in tiny amounts, so it's effectively breathing.  Mix that with how brake fluid has a penchant for moisture, and Robert's your Mum's Brother.

 

Gaz 

Whenever you use your brakes, the discs/pads heat up a lot, the pads pass some of the heat to the calipers which also heat up. The brake fluid in the calipers expands and the level in the reservoir rises pushing some air out through the small vent in the cap. When the brakes cool, air is drawn back as the fluid cools. So its breathing the atmosphere constantly and a tiny bit of moisture absorbs into the hygroscopic brake fluid. Depending on how aggressive and frequent the braking occurs  and atmospheric humidity, the water content in the fluid rises over time.

I have gone over 10 years with cars i have had from new and never changed brake fluid in my own cars,

i have a 15 year old one still with the original brake fluid and no replacement pipes or hoses, and only one set of discs and pads fitted in the 15 years, not ever bleed in that time, & it has done under 60,000 miles.

but i have a Brake Fluid Tester and check the H2o content in the brake fluid.

 

I would not be leaving cars that i bought as a used car with the brake fluid that they come with.

Those testers seem to vary from £3  to £400 from a quick headline Google  search.

Any water in the braking system will decrease the boiling point of the fluid.

How much water contamination is acceptable? Day to day driving puts different demands on the system compared to repeated downhill braking fully loaded, stuck behind a slower vehicle. I had brake fade, my one and only time, under those circumstances.

Hmmmm, I think I'll take note of this 1 after all, some have accused me of being a bit heavy on the brakes

The cheaper testers just test conductivity, the more expensive ones actually give you a boiling point figure to check against the spec of the fluid in use. 

 

Like anything these days brake fluids are complex chemicals and there are good ones and bad ones. Moisture is not the only problem, modern brake fluids contain all kinds of things like anti-corrosion inhibitors, pH balancing additives, anti-foaming additives , viscosity stabilizers etc etc. These can break down with use and abuse as well. Like anything cheaper fluids will break down earlier with less abuse, better fluids last longer.

 

How long you can leave it in or what is an acceptable drop in boiling point is quite subjective involving a lot of opinion. It depends on the use or abuse the brakes get, the quality of the system, the quality of the fluid and the original spec boiling point.

 

If you don't know the answers to questions like that, then IMHO best just to change it or get it changed. 

 

ATE blue never let me down (just shame its not blue any more)

It's not just brake fade that you need to worry about re brake fluid (although fade isn't always brake fluid related - can be related to disks/pads that are worn out and overheating). Absorbed water/chemical breakdown can cause other issues - master cylinder pitting, wheel cylinder or calliper corrosion, internal rusting of brake pipes ( a friend of my father was killed in an old Mini that had brake failure because of this) and damage to brake components such a ride height valves, ABS units, dual circuit failure detection etc...

 

One thing that is really important - if you are going to store a car for a while change the engine oil and brake fluid. Somehow damage accelerates when not used - I've seen the crap that drains out of cars of a certain age and it's not pretty - sometimes it's milky, sometimes it's stained with rust  and what came out of a Volvo 740 looked like Miso soup.

Edited 5 August, 20187 yr by bigjohn

.,.. which is why before I recommission the A2, one of the things that will be changed is the brake fluid. I don't like how spongy the brakes are at the moment, but that may also be due to rust. 

I might get the fluid changed for peace of mind - and an assured roadworthiness test pass - before the test. I suspect it will pass anyway, but I do have to do some kilometres beforehand and it's about time both engine oil and brake fluid were changed. They've been sitting for too long and are definitively past their best.

 

 - Bret

BRAIN fade is even more dangerous than BRAKE fade judging by the number of accidents I see on our motorway network with people driving too fast, too close, undertaking and not indicating when changing lanes. Feel better now that's off my chest!

Offski's reply above is 100% correct.  Here in the UK the new MOT will prove interesting because (at least it's my belief) they'll be checking the water content of the brake fluid.

 

All I'll say is I have 35 years of driving experience and I've yet to read anyone's brakes failing because the fluid wasn't changed. I know many people who couldn't care less about their cars - I've seen some unhealthy cars due to lack of maintenance but I've yet to see any of their brakes failing. And thru personal experience, the only time I've been genuinely frightened in a car was when some mechanical genius changed my brake fluid (I didn't know they'd changed it) but hadn't bled the brakes properly.

 

If garages would test the fluid then recommend it be renewed, I wouldn't give a 2nd thought to changing it,  but as long as they want to change at set intervals - it's not going to happen. Is it a rip off? I believe it is.

 

PS - 3yr from new then every 2yr. Used to be every 2yrs so why the change to 3?  And why not every 3yr thereafter?  If anyone is going to answer this are they able to back it up with evidence rather than giving their best guess or gut feeling? I've yet to read a definitive answer why the change was made.

Edited 6 August, 20187 yr by Guest

22 hours ago, bigjohn said:

One thing that is really important - if you are going to store a car for a while change the engine oil and brake fluid. Somehow damage accelerates when not used - I've seen the crap that drains out of cars of a certain age and it's not pretty - sometimes it's milky, sometimes it's stained with rust  and what came out of a Volvo 740 looked like Miso soup.

 

I don't doubt that for a second and it's good advice. But the question is, does Miso soup stop the car?  As per my answer above - my issue is that people are changing things without testing.

 

After two years from new, a garage recommended a brake fluid change. I refused on the basis I was happy with my brakes. I said that if I detected they weren't working effectively I'd have them looked at / fluid changed. The reply I got was startling. They told me I wouldn't experience any degregation - my brakes would work 100% one second but experience total failure the next due to water content.  So I asked them to test the current water content of my brakes.  " Oh we don't do that sir, we just replace the fluid as routine ".

 

As the expression goes in these parts  - "do you think I came up the Clyde in a bananna boat?"

52 minutes ago, Scot5 said:

As the expression goes in these parts  - "do you think I came up the Clyde in a bananna boat?"

 

 

Banana boats are well managed and maintained ships.

The old saying was "do you think I came up the Clyde in a Spam tin?"

43 minutes ago, Scot5 said:

Offski's reply above is 100% correct.  Here in the UK the new MOT will prove interesting because (at least it's my belief) they'll be checking the water content of the brake fluid.

 

All I'll say is I have 35 years of driving experience and I've yet to read anyone's brakes failing because the fluid wasn't changed. I know many people who couldn't care less about their cars - I've seen some unhealthy cars due to lack of maintenance but I've yet to see any of their brakes failing. And thru personal experience, the only time I've been genuinely frightened in a car was when some mechanical genius changed my brake fluid (I didn't know they'd changed it) but hadn't bled the brakes properly.

 

If garages would test the fluid then recommend it be renewed, I wouldn't give a 2nd thought to changing it,  but as long as they want to change at set intervals - it's not going to happen. Is it a rip off? I believe it is.

 

PS - 3yr from new then every 2yr. Used to be every 2yrs so why the change to 3?  And why not every 3yr thereafter?  If anyone is going to answer this are they able to back it up with evidence rather than giving their best guess or gut feeling? I've yet to read a definitive answer why the change was made.

 

Not changing brake fluid allows it to absorb more moisture over time. The more it absorbs the softer the pedal becomes decreasing braking performance which is more noticeable than lowering the boiling point of the fluid as most drivers won’t get their  brakes that hot anyway. 

The braking system has many parts that corrode from moisture in the fluid especially the brake lines which are still made from mild steel and painted on the outside to protect from the elements but not the inside.

The first change at three years is since it was filled in a new system, free from contamination. The fluid will start to cause corrosion, which contaminates the fluid even more. Replacing the brake fluid into a system that already has small amounts of corrosion won’t last as long as the first fill hence 3 years then 2 thereafter. 

If you don’t want to spend the equivalent of a tank of fuel every two years to keep your brakes in optimum condition that’s your choice. I do mine myself at least every two years which costs me less than £5 a year. I also clean and lubricate the calipers at the same time to keep the brakes at an optimum as it’s about the preventive maintenance too. 

31 minutes ago, gregoir said:

 

 

Banana boats are well managed and maintained ships.

The old saying was "do you think I came up the Clyde in a Spam tin?"

 

Up the Clyde in a spam tin? Never heard that b4 in my life. Our generation never used that expression.

 

The bananna boat point is about being naive or being easily conned  -  it's has nothing to do with the ship.

2 minutes ago, Scot5 said:

 

Up the Clyde in a spam tin? Never heard that b4 in my life. Our generation never used that expression.

 

The bananna boat point is about being naive or being easily conned  -  it's has nothing to do with the ship.

I think you fell over his banana skin joke!

53 minutes ago, CWARD said:

 

Not changing brake fluid allows it to absorb more moisture over time. The more it absorbs the softer the pedal becomes decreasing braking performance which is more noticeable than lowering the boiling point of the fluid as most drivers won’t get their  brakes that hot anyway. 

The braking system has many parts that corrode from moisture in the fluid especially the brake lines which are still made from mild steel and painted on the outside to protect from the elements but not the inside.

The first change at three years is since it was filled in a new system, free from contamination. The fluid will start to cause corrosion, which contaminates the fluid even more. Replacing the brake fluid into a system that already has small amounts of corrosion won’t last as long as the first fill hence 3 years then 2 thereafter. 

If you don’t want to spend the equivalent of a tank of fuel every two years to keep your brakes in optimum condition that’s your choice. I do mine myself at least every two years which costs me less than £5 a year. I also clean and lubricate the calipers at the same time to keep the brakes at an optimum as it’s about the preventive maintenance too. 

 

Yep heard it all b4.

 

As I replied earlier that 'spongy' feeling doesn't exist according to certain garages - one minute you're brakes are 100% effective, next you're going to plough in to a brick wall apparently. I'd sugest these are garages who either dont know how brakes work or are simply frightening you in to parting with money. Or both.

 

The three years thing I get but you you haven't explained why after 30 odd years, they've changed from two years to three?  (Before 30 odd years, I can't recall anyone mentioning ever mentioning brake fluid change - all of a sudden this two year rule was introduced. If I remember rightly, the two year rule co-incided with longer service intervals (used to be every 5k or 6k). Being a sceptic, I'd suggest it had more to do with generating revenue to compensate for the longer service intervals but have no proof whatsoever.

 

I know people change it every two years, there's nothing wrong with that whatsoever, but I've yet to hear anyone who's brakes have failed due to water ingrees. The point is does it need changing? Have you ever checked the water content in the brake fluid you've thrown away after 2yr?  Who's to say the fluid in your car isn't as good as the day it was installed.

 

As per above, will be very interesting to see how many 3yr old cars (other manufacturers say every 2yr from new) or 4 or 5 or 6 year old cars fail their MOT because of water ingress. As far as I'm aware it's the first time anyones studied it because thus far it's all theory and gut feeling.

Edited 6 August, 20187 yr by Guest

IT's always about increasing revenue for garages/business in general. Milk the customer and tell them their life/safety depends on it. Imagine the cost of replacing the 7 airbags in an Octy, probably write the car off first.