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Brake fluid change intervals - waste of money for most?

MSG2004

MB Enthusiast
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GLE Amg-Line C Class Avantgarde C class Classic Auto Mondeo Ghia V6 Audi 2.3 Ford Sierra V6
I've just watched a video on YT
The chap used a tester on new and ten-year-old brake fluid
Both showed the ok/green light

IMO, it's an easy money maker for the dealers and fast fits

I sold my C class Avantgarde/petrol in spet 2016 - it had regular oil changed, about 12/13 months but the brake fluid had not been changed for 5
years. IIRC I was doing about 7/8k miles a year
In 2016 April I bought a brand new gle- diesel - the first year I did 6/7k miles the about 2.5/3k miles a year on average atm the total miles is just over 23k.
The car has had 3 brake fluid changes - an over-kill IMO and a money spinner for the business people.

My car is due a B service this month - I'll wait until early March and get the oil done as well as filter and that is about it. My car is rarely thrashed, 99%
of the time driven gently -

I am aware car's the warranty and manufacturer's criteria to retain the warranty etc

So is it a waste of money changing this at 2 years if you don't drive a lot and the warranty is not affected
 
Brakes would work even if the system was full of water , they just wouldn't be very effective at dissapating heat draw and would boil if the brakes were being hammered, then simply wouldn't work at stopping you at all , but who does that though in normal driving ?. The brakes on the wife's Kuga went untouched in 8 years and we're still $hit hot . It's all down to uttermost safety in all conditions isn't it.
 
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I am aware car's the warranty and manufacturer's criteria to retain the warranty etc

So is it a waste of money changing this at 2 years if you don't drive a lot and the warranty is not affected
Had many second hand cars in my youth, and never changed brake fluid in any of them. Never had any brake problems either beyond pads needing replaced. Don't think I've ever had discs replaced either until they removed asbestos from the pads, discs can now wear out very quickly compared to before.
 
Brakes would work even if the system was full of water , they just wouldn't be very effective at dissapating heat draw and would boil if the brakes were being hammered, then simply wouldn't work at stopping you at all , but who does that though in normal driving ?. The brakes on the wife's Kuga went untouched in 8 years and we're still $hit hot . It's all down to uttermost safety in all conditions isn't it.
Safety is assured if you test the fluid or have it tested.
The more I read on this here and the net, the more convinced I am that is it a almost as good easy money for the garages.
 
The whole - "the car says so" mantra of modern vehicles is becoming a bit of a joke :

My BMW 440i has had the oil replaced three times , brake fluid changed three times , plugs replaced , air filter replaced twice - in 11,000 miles - because the car said it needs them done.

My Cayenne needs the oil replaced every year despite it having covered a mammoth 2500 miles , however the transmission oil only needs replaced at 160,000 miles - because the car says so.

K
 
I've always taken the opinion that the only way water can get into a properly maintained brake system is through the breather hole on the reservoir, where a tester would find it straight away. Hence like many others my opinion is that it's purely a money spinner for workshops especially main dealers and cars still under warranty - and as neither of my cars are that I ignore it! Bloody things are expensive enough without un-necessary money spinners!
 
I agree that as long as the water content in the brake fluid is within the permissible range, and the fluid is clean of debris, it can be used regardless of how long it was in the car.

However, the issue with the hygroscope test is that people usually test the fluid in the reservoir, which is rarely contaminated. Almost every hygroscope test I've seen on YouTube was done at the reservoir, and almost all tests were within the range.

But you need to keep in mind that brake fluid isn't coolant, and there's no circulation pump. The brake fluid does not circulate in the system. What you should really do is bleed the four brake calipers and perform the test on samples from each caliper.

I have seen many cars where the brake fluid in the reservoir was nice and clean, but when bleeding the callipers, the first dose was murky.

At this point, for the small extra cost, you might as well just continue bleeding and change the fluid....
 
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So if none of the above problems present themselves, then your brake fluid is fine and doesn't need changed, that's effectively what your telling us!

The post you quoted is "AI generated."
The brake fluid is clearly a con, money spiner as I proved in my C class and some other cars as have others.

I keep my cars in tip-top roadworthy condition and ensure that my wippers/brakes/lights/tyres/etc are in good condition.

Someone needs to ask the service tech that is looking after your car - why change fluid every 2 years when the brake fluid tester has told you that the fluid is 100% puka
 
I agree that as long as the water content in the brake fluid is within the permissable range, and the fluid is clean of debris, it can be used regardless of how long it was in the car.

However, the issue with the hygroscope test is that people usually test the fluid in the reservoir, which is rarely contaminated. Almost every hygroscope test I've seen on YouTube was done at the reservoir and almost all tests where within the range.

But you need to keep in mind that brake fluid isn't coolant, and there's no circulation pump. The brake fluid does not circulate in the system. What you should really do is bleed the four brake calipers and perform the test on samples from each calipers.

I have seen many cars where the brake fluid in the reservoir was nice and clean, but when bleeding the callipers the first dose was murky.

At this point, for the small extra cost, you might as well just continue bleeding and change the fluid....
Good point, but just because it’s dirty doesn’t mean it has deteriorated due to any water, is the murky colour just due to the rubber hoses and seals ?
If any water has entered through the reservoir it would never get to the calipers.
I have a 24 year old motorbike that only ever had the brake fluid changed once at last year, the brakes are worked hard and never suffered brake fade before the fluid changed last year,
 
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I agree that as long as the water content in the brake fluid is within the permissable range, and the fluid is clean of debris, it can be used regardless of how long it was in the car.

However, the issue with the hygroscope test is that people usually test the fluid in the reservoir, which is rarely contaminated. Almost every hygroscope test I've seen on YouTube was done at the reservoir and almost all tests where within the range.

But you need to keep in mind that brake fluid isn't coolant, and there's no circulation pump. The brake fluid does not circulate in the system. What you should really do is bleed the four brake calipers and perform the test on samples from each calipers.

I have seen many cars where the brake fluid in the reservoir was nice and clean, but when bleeding the callipers the first dose was murky.

At this point, for the small extra cost, you might as well just continue bleeding and change the fluid....
Good post but most of us can tell if brakes are not up to par.
The video I saw the tester was used on drained fluid that was 5 years old

I'm certain that brake fluid changes on car that are not that old and driver 4/5k or less a year don't need a fluid change.
 
A friend of mine has been told his jaguar is now due for all flexible brake hoses to be changed as part of his next service. It’s 6 years old and done 37,000 miles, he was quoted £990 for the service.
 
A friend of mine has been told his jaguar is now due for all flexible brake hoses to be changed as part of his next service. It’s 6 years old and done 37,000 miles, he was quoted £990 for the service.
My Kawasaki service schedule says the radiator hoses should all be replaced at the 4th year service, the high pressure fuel hoses at the 6th year service. Mine is now 6 years old, only done 4600 miles, none have been changed. I think I see a pattern here?
 
So is it a waste of money changing this at 2 years if you don't drive a lot and the warranty is not affected

Conventional brake fluid absorbs water and just as important the corrosion inhibitors get depleted over time. That said a 2 year interval is probably over kill and not absolutely necessary. It could be changed on a longer interval or based on condition monitoring. Personally I wouldn't miss a minutes sleep if I changed at 3 years instead of 2 years. The limited testing I've done backs that up.

Anecdotal evidence that a 2 year change interval could be too cautious comes from the US. If you read US automotive forums the culture of regular fluid changes just doesn't exist to anything like the same extent over there and that's among motoring enthusiasts. I don't see any evidence US cars are more prone to brake failure than ours. Possibly a drier environment helps the fluid last longer.

The main thing is to change it even if it's not super critical to do it at exactly 2 year intervals.
 
Good post but most of us can tell if brakes are not up to par.
The video I saw the tester was used on drained fluid that was 5 years old

I'm certain that brake fluid changes on car that are not that old and driver 4/5k or less a year don't need a fluid change.

The fact that one person checked the drained brake fluid on one car and it was fine after 5 years is neither here nor there.

The question is how do you know that the brake fluid in your car is OK?

If you check at the reservoir, then that's no good.

If you have to drain the fluid to test it.... that's no good either :D

I don't disagree that 2 years interval is arbitrary. Some marques quote 3 years, and they all use the same type of brake fluid.

My point is that for the cost, replacing it every 2 years (or 3 years) is a sensible precaution.

And, BTW, my local ATS branch (now closed) had brake fluid change for £35 on their price list.

Seems penny pinching to me to not replace the fluid, using YouTube videos as justification. No offence meant.
 
As a general guide I do a fluid change with every brake pad replacement. Now doing much lower annual mileage, so I may have to change the plan. A litre pushed through via the bleed nipples every two years should keep things in good order.
 
There’s a very high probably that brake fluid will still be perfectly functional long after 2 years, the same for engine oil after 1 year, spark plugs after 3/4 years, air filter after 4 years, transmission fluid after 37,500 miles, coolant after 15 years, etc.

Most cars are not serviced in line with the schedule, and keep running just fine. Not optimal, but sufficiently functional to keep going. Until they stop running just fine and something fails resulting in a repair or some kind of accident.

Like all aspects of scheduled services, replacing the brake fluid is a preventative maintenance, and preventative maintenance is a risk mitigation strategy to avoid expected issues/incidents occurring at a time when you least want them.

Like an emergency stop.

For a car, performing scheduled maintenance certainly costs more than not doing it at all. You can save a fortune by not servicing the car, more than you’ll spend on repairs and lose in value, especially if you pay someone else to do it.

Personally, I service according to the schedule.
 
Personally, I service according to the schedule.

When the car is new, newer I do. My current car is the most expensive car I've owned and only my third car that I've bought brand new.
As I felt it was a complexed car compared to my other cars inc 2 MB's, I not only stuck to the servicing schedule for warranty sake but
spend a bit more now then hope it stays good - this is the 8th year of ownership and the car has certainly been over-serviced re brake fluid and air and pollen filters as the mileage now at over 8 years old is 23k+ - IMO, and all agree here is the brake fluid change at 2 years is overdone.
I'll add to that the air and pollen filter as well for my cars as I don't live in the desert etc where there is a lot of dust etc.

As I've said, may previous car a c class petrol sold at 7 yrs old did not have the fluid changed for several years nor air or pollen filters all was good and I had intended to sell the car so it was less worry.

Changing brake fluid every two years along with air and pollen filters is IMO an over kill but you have little option if you want to retain your warranty and the main dealers along with fast-fits etc benefit from this as well as those that make the parts.
 
Re brake fluid, air and pollen filters etc. A very sensible post from our mutual friend, Mr AI

AI Overview
Learn more

While changing brake fluid and air filters every two years is often recommended by garages, some argue that it can be considered a "money-making exercise"because in many cases, the fluid and filter may not need replacing that frequently, and testing their condition is often a better approach than simply adhering to a strict two-year schedule; a reputable mechanic should assess the components before recommending replacement.

Key points to consider:
  • Brake fluid absorbs moisture:
    The main reason to change brake fluid is that it absorbs moisture over time, which can affect braking performance; however, testing the fluid's moisture content can determine if it needs replacing, not just relying on a time-based schedule.

  • Air filter condition matters:
    While an air filter should be checked regularly, a clean filter doesn't necessarily need replacing every two years if it's still functioning well.

  • Driving habits and environment:
    Factors like driving conditions and climate can influence how quickly brake fluid degrades
    and how often the air filter needs changing.



Generative AI is experimental.
 

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