How much brake fluid?

Soldato
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So I'm going to do a few little service bits on my ZS. I'm going to replace the brake fluid, how much new fluid will I need to buy? I have looked in the Haynes manual but it has every reservoir except the one I need :rolleyes:
 
The manual won't tell you how much fluid is in the reservoir as this is a useless bit of information - most of the fluid is within the master cylinder, pipes and the slave cylinders/calipers. 1 liter should be enough to completely replace all the fluid in the system with some left over for bleeding - but if you have any problems bleeding you could go over this.
 
What Dogbreath said - I recently did mine from empty and its just under a litre, but needed 500ml more to bleed it.
 
5L????

When i bled through the RS4 I bought 2 litres and ended up using about 750ml. Now considering they are massive 8 pots on the front and big 2 pots on the rear I can't see how any other system would use more!

I would also recomend a pressurised bleeder that you attach to a wheel. They can be found on a popular auction site!
 
Why?
Once opened you can't keep the stuff for ages as it absorbs water.

As you only change brake fluid a few (if any) times in the car's life the fluid would be sat around for 5+ years until it would be used again.

It wont absorb water if the container is kept with the lid on.
 
Unless it is 100% air tight (which it won't be, ever), then it WILL absorb moisture from the air.

The fluid sits in the bottle on the shelf for years it isnt bottled under a vacuum. Putting the lid back on tight will stop moisture in the air from entering the bottle, apart from whats in the bottle when you put the lid on and thats not anywhere near enough to worry about.

If that was the case then you wouldn't ever need to change the brake fluid in a car.

The brake fluid in your car isn't sealed, the reservoir has a hole in it to allow air in as the brake fluid level drops when the brakes wear. The brake system is a very harsh place to keep fluid thats another reason you change it every two years. It's not the same as putting the lid back on the bottle tight and keeping the fluid.
 
The fluid sits in the bottle on the shelf for years it isnt bottled under a vacuum. Putting the lid back on tight will stop moisture in the air from entering the bottle, apart from whats in the bottle when you put the lid on and thats not anywhere near enough to worry about.



The brake fluid in your car isn't sealed, the reservoir has a hole in it to allow air in as the brake fluid level drops when the brakes wear. The brake system is a very harsh place to keep fluid thats another reason you change it every two years. It's not the same as putting the lid back on the bottle tight and keeping the fluid.

Lol wtf?!!?

1) All brake fluid comes with a secondary seal like food to keep air out, as well as the cap.

2) what makes you think the tiny amount of air in the top of the container contains moisture? Pretty much every packaged food substance you can buy is preserved with Nitrogen in the packaging, I would imagine its the same for how they package brake fluid.
 
The brake fluid in your car isn't sealed, the reservoir has a hole in it to allow air in as the brake fluid level drops when the brakes wear. The brake system is a very harsh place to keep fluid thats another reason you change it every two years. It's not the same as putting the lid back on the bottle tight and keeping the fluid.

Changed mine after 9.5 years and the brakes feel the same as they did before.
The every two years thing is massively OTT (btw my Haynes says every 2 years, but also says oil every 8000 miles :p).
 
Changed mine after 9.5 years and the brakes feel the same as they did before.
The every two years thing is massively OTT (btw my Haynes says every 2 years, but also says oil every 8000 miles :p).

You cannot possibly state that every two years is OTT, as have you analysed brake fluid from every brake system out there?

After 2 years the wet boiling point is MASSIVELY down on what it would be from new in pretty much any car.

I used to work with brake fluid testers, which tested the wet boiling point and some of the figures were shocking. Sure the brakes feel normal when cold... but thats not what the brakes are going to be in an emergency.

This is the reason for the change. In addition, as the boiling point is greatly reduced, this makes the brakes less effective, and means you will get corrosion in the brake system, especially after such a long time.

Suggesting to people that 9.5 years is ok is not a very clever thing to do. I just hope nobody listens to that.
 
Yes it will.

Its pretty hygroscopic.

5L is pure lol. Total waste unless you can do another car too and make the most of it.

Hope it wasnt expensive stuff.

It doesn't suddenly absorb loads of moisture once you let air come in contact with it. If you put the cap back on tight no moisture can get in there, its a sealed container. You can tip the container upside down no fluid will come out, put it in a bucket of water and no air will escape same as if its left on a shelf no moisture will get in.
 
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