How Long Does Brake Fluid Last

[ReganAndCarter]

Another question for the experts, please. I bought my Scudo van 13 years ago, and it's now almost 16 years old. The brake fluid in the system is the same as when I bought it, and may well be the original from the Fiat factory. The odometer has just hit the magic 100,000 miles.

My question is - how long does modern brake fluid last? The brakes work fine, with no sponginess.

Over to the experts.

 

[Burnerman]

Manufacturers like to change the brake fluid every two years.....of course, they are happy to charge for this!
However, brake fluid does absorb water, and that could theoretically boil under severe braking - their argument, of course!
Personally I change the fluid when I replace pads and discs, and that keeps the caliper nipples free which can be important, so lets say 3 years.
I like the Gunson Eezibleed system that works off tyre pressure at 20 psi. A simple, one man task so long as the bloody bleed nipples open!
John

 

[Stivino]

My question is - how long does modern brake fluid last?

At least 16 years

 

[Harry Bloomfield]

When I replace my cars with another, I always flush and replace the fluid. Moisture is absorbed as the level falls, as the pads wear, which draws moist air into the reservoir, plus some absorbtion through the seals. In heavy brake use, moisture in the brake fluid can boil, which results in no effective brakes.

If I keep a vehicle a long time, or the fluid shows obvious signs of contamination, then I would change it. I certainly would not run a vehicle 100K without replacing the fluid.

 

[Mottie]

Even dirty black brake fluid can lead to an MOT failure nowdays. Whenever I change fluid, I always remove the reservoir, wash it out and dry it thoroughly before topping up and bleeding through until running clear.

 

[Tigercubrider]

DOT 5 doesn't absorb water

 

[Mottie]

DOT 5 doesn't absorb water

True, but it’s expensive and if you use DOT 5 you will need to completely flush the system and change all your seals as it won’t mix with DOT 3/4. Best avoided unless used in a totally new build brake system on a race car.

 

[Stivino]

DOT 5.1 is mixable with DOT 4

 

[nauseous]

Good luck opening the 4 nips, they might be a bit stiff. Take your time and use a good type of
penetrating oil the day before tomorrow.

 

[Mottie]

DOT 5.1 is mixable with DOT 4

And DOT 3 because it’s similar to 4/5.1 and is not silicone based.

 

[Harry Bloomfield]

Good luck opening the 4 nips, they might be a bit stiff. Take your time and use a good type of
penetrating oil the day before tomorrow.

If I struggle with a nipple, I just heat them up and allow them to cool, using a pencil blowlamp. A fraction of a turning tightening them, then try to undo - often helps.

 

[ReganAndCarter]

Thanks for all your replies, really appreciated. With also be very gentle with stiff nipples.

 

[nauseous]

If I struggle with a nipple, I just heat them up and allow them to cool, using a pencil blowlamp. A fraction of a turning tightening them, then try to undo - often helps.

A pencil blowlamp sounds a great idea. I tried heat on my ancient blingo's front calipers, a standard blamp will most likely distort or melt the rubber seals. Didn't work anyway, never did get them out.

 

[nauseous]

A 50/50 mix of brake fluid and acetone mixed in a glass jar is supposed to be a really good penetrating oil.
Also a 50/50 BF & ATF oil is supposed to be good. Be careful tho as both of these will wreck paintwork obv
as well as your skin!



edit; acetone (sometimes used in nail varnish remover)not acetate

 

[HERTS P&D]

Good luck opening the 4 nips, they might be a bit stiff. Take your time and use a good type of penetrating oil the day before tomorrow.

I can always recommend lubrication on the nipples.

Andy