Dot 5.1

[silverzx]

Does it corrode any of the pipes or anything? Been using it for some time and I appear to have a minor leak on the passenger side front brake line which may of been caused by this?

Also the brakes feel pretty shoddy and I only changed the discs and pads not that long ago for 266's instead of 247's!

[Niall]

Nope it won't corrode any pipes. Get the leak repaired and do a full flush with some fresh fluid. That could make a big difference to the feel of your brakes.

[Grant]

^^^^ Dafuq?!

When i bought a bottle of it you made a big thing of it ruining the braking system...

[Niall]

^^^^ Dafuq?!

When i bought a bottle of it you made a big thing of it ruining the braking system...

You bought silicone based fluid which can ruin seals depending on what they have used when the car was built.
Standard recommendation is dot4

[Grant]

Specifically says on the bottle non silicone based...



Straight from the Halfords website...

The Halfords DOT5.1 High Performance Brake & Clutch Fluid has a non silicone base and is recommended for vehicles with ABS. It meets and exceeds Super DOT4 specification.

[Matt]

[Grant]

Right, thought I'd clear this up as it is bugging me. There is no conclusive answer on the internet to:

'Will dot 5.1 fluid damage braking systems'

But after scouring wikipedia and other such resources, I have learnt the follwing;

Peugeots, run out of the factory with what is called LHM (Liquide hyraulique minerale (some frecnch shit for mineral hydraulic liquid)) fluid in the braking system. LHM fluid was created by citroen in 1954 and in its basic form it is not hygroscopic. This means it does not naturally adsorb water from the atmosphere. Ideal in braking and suspension systems obv, as less gas bubbles will form in the system, reducing braking or compression efficiency.
Because it is a mineral oil, it, as above, adsorbs minimal moisture and also contains corrosion inhibitors. This means it remains less corrosive for longer periods of time. We all know brake fluid is corrosive, excellent at removing paint from that twat of a neighbours car, but LHM will do consequentially do less of this. Hence requiring changing less, lengthening the life of the system.
As the LHM is a mineral based oil, it requires different seals to those system running silicone of other synthetic based oil systems.

Dot 4 will be fine in your system, however, as the peugeot, citroen and some rolls-royce braking sytsems use what are known as LHM seals, 5.1 will corrode these, breaking them down over time, hence causing system leaks. For this i do not however know a time-frame. It could be minutes, hours, weeks or even years....
Dot 5.1 is not a mineral oil, so this is why it has this effect.

And of course, do not mix types of fluid, make sure your system is flushed correctly...


Hope that helps

[Niall]

I was always told by my mot tester that the reason you shouldn't mix 5.1 is because it is silicone based and most systems, unless designed for it, can deteriorate seals and pump internals. It can also cause issues with different boiling temperatures if mixed.
I've never heard a problem with doing a complete flush with 5.1 but personally, I wouldn't want to.