Brake Fluid Change
My Ford Mondeo has a service interval of every 2 years or at 18,000 miles whichever is the sooner. I have been told that Ford now recommend a change of brake fluid every two years - ie at every service in my case. This seems to be a new recommendation. Is it common with other makes of cars or is it just another main dealer rip off?
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It’s not new. My Ford dealer tried to push for a brake fluid change every time I had my Focus serviced and that was annually. I had it done after about 3 years.
Only you can decide but my feeling is that it would be included in the service if it was essential.
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Good point about it being included in the service if essential, TW. I did have it done at the previous service when it was 'recommended'. That was at 29,500 miles. I've now only done a further 16,800 miles and the dealer has recommended it again.
Thinking back to may early years and maintaining my own cars, my dad, an Army vehicle mechanic, told me the fluid needed changing if the brakes started to feel a bit spongy and about every five years or so otherwise as the fluid absorbed water. I would have expected modern fluid to have improved in quality not, apparently, got worse.
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In my opinion the fluid is more likely to deteriorate on a low mileage car than a high as it becomes prone to collecting condensation, and near on 17k miles in two years isn’t particularly low mileage in my book, John,
Our car (Hyundai) has done about 7k in two years and the fluid was changed as it was included in the service. 🤷🏻♂️
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In my opinion the fluid is more likely to deteriorate on a low mileage car than a high as it becomes prone to collecting condensation,
Not disagreeing but it seems strange. A brake system is bled of air and is largely a contained system filled with brake fluid. The condensation comes from water vapour in the air. How does that enter the system? The only air fluid interface might be thought to be the breather hole in the reservoir. Any water vapour entering will be a very small amount and the water is lighter than the brake fluid.
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As above, brake fluid is hygroscopic ie absorbs water. Dealers & garages cover their bum by recommending a fluid change at 2 years irrespective of mileage. There are testers though that will check for water in the fluid ... how good they are, I've no idea.
I'd be dubious of whether a complete change is ever done these day as there is a load of fluid in the ABS modulator that needs pumping through too ...
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Brake fluid can become hot under extreme conditions and it is designed to accommodate this however, if it regularly gets hot some constituents will be expended. It will discolour and possibly air bubbles will introduce more corrosion. in short is can deteriorate. However, modern braking systems are so well advanced and such great margins provided that non of these degrading processes are likely to the average motorist. The service engineer may recommend it but only after inspection. The service receptionist may offer all sorts of extras- new coolant sir? All the same - lovely extra profit. My advice is to stick strictly to the service schedule and no more or less.
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Some armchair mechanics actually are qualified and experienced in the subject. Even in the design and development of them. Even having a spent over 40 years in the profession. Not all, but some.
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As has been correctly pointed out earlier most, automotive use brake fluids, are "hygroscopic", they can absorb water, into solution.
This brings two ramifications, one potentially safety critical, the other a cause for incipient corrosion.
The big danger is the water in solution can boil, at quite a bit lower temperature blowing out the vital liquid so next time you plant your foot you have no braking. Without the water the system design should never reach the boiling point of the fluid.
The obvious second issue is water supports corrosion so overtime there will be brake failure arising from that.
Some systems don't have an air vent and are sealed from this issue by an air to fluid diaphragm.
Fluid change time is an estimate, a challenging one to make as there are many variables, where used, frequency of use, humidity and probably many more.
I suspect the vehicle makers cover the worst possible combination recommending a change time that they feel presents no risk, whilst not overly adding to user costs.( they must do this as many fleet users pay great attention to through life ownership costs)
Me I am a three year change on brakes, 6 on clutches, not that I recommened you do anything other than what the maker suggests.0 -
I agree with those who say the fluid is hydroscopic. It does absorb water from the atmosphere. Many years age a chap I worked with whose job was to examine vehicles involved in road collisions was issued with a new bit of kit to test brake fluid for water content and deterioration.
So out of interest I tested my own vehicle which was about 5 years old and had never had a change of fluid. The fluid was contaminated badly with water and not up to the job it was designed to do so I had it changed immediately.
Water in brake fluid when over heated by braking will boil and they will not work, this is called brake fade.. You cannot compress a fluid but you can compress a gas or vapour.
My own vehicle brake fluid is changed every two years. I recommend you err on the side of safety.
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I have the fluid in our cars changed every two years regardless of whether specified or not. Its hygroscopic nature means that there is a risk of it accumulating water which will corrode the bores of calipers. Like lots of things with cars, if one is going to keep them it's worth doing preventative maintenance
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You must drain down properly . Most dealers dont so its a waste of money .Brake fade is bad , but why do people drive flat out up to junctions , slam on brakes ? Then wonder why pads dont last I . still drive old way slow down change down , if clear accelerate away ,less wear and tear
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Reading all your comments and looking at other motoring forums it appears that different makes of car 'recommend' a change of fluid at various different intervals. As a result I've decided to get mine changed next year at three years since the last change.
My new service plan taken out yesterday now includes brake fluid change which, the dealer suggested, I get done in 1 years time when the car goes in for an interim check as part of the plan. "3 years between fluid changes is fine" he commented ! What is even better is that the plan gives me even more benefits but remains at the same price as the previous plan. Aren't I glad I declined to have it done at the last service at an extra cost of £35.
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I always change my brake fluid every two years, both motorbike and cars. It takes less than an hour and costs less then a tenner if you do it yourself. Why wouldn't you chnage it? As for how does the water get in there. There is an air hole in the lid of the master cylinder, plus, whenever something metal warms up and cools down it creates condensation. Brakes heat up and cool down many times on every journey.
Noot only can water not be compressed, but it causes corrosion inside the brake system. Someone mentioned you can't get all the fluid out because of the ABS modulator. Some cars need to be plugged into a computer to purge the system, but most cars just need a simple old fashioned bleed.
I actually use a vacuum bleeder. Pump it up and simply fill the reservoir while the bleeder sucks the fluid through.
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https://www.halfords.com/workshop-tools/tools/hand-tools/gunson-eezibleed
had one of these for years. makes job a lot easier and can do on your own.
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Never got on with one of those, free to anybody who wants it. It put more air back in the system than I got out. Also, risk of spraying brake fluid everywhere. No substitute for the OH sat in the car pumping the pedal - works perfectly every time. That said, my experience is with 40+ yr old cars, so maybe more to it with modern vehicles?
I was under the impression that modern vehicles used silicone fluid as standard and have done so for some time (not interchangeable with the mineral based variety). In which case, all this stuff about hygroscopicity and related problems isn’t relevant (as per DDs link). However, no doubt the modern stuff degrades over time?
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