brake fluid

[grahambiddulph]

Anyone know if its alright to put silicon brake fluid in if you have just pumped out

the old fluid i.e. it will still have traces of old fluid in the system.

 

I suppose what I am saying is, do they mix. *confused*

[rj]

In my experience,

 

No 😔

[mav]

It's evil in my opinion.

 

Best off sticking to dot 4 or 5.1

[Pezky]

I have used Silicone brake fluid for a couple of years now, have not had any problems with it- using standard calipers.

When I replaced it, I drained all the old stuff out, then bled system with silicone.

I know a few other owners of "lightly used" cars are using it, I found it better than having to bleed the brake system every year.

 

[Bricol]

There is a theory about silicon fluid - as it is non-hydroscopic (it's main selling point), water that un-avoidably enters the braking system simply moves down to the lowest point in the system - where it sits and corrodes the metal around it. The lowest points normally being the calipers.

 

Plus water now sat in the calipers boils even easier than common old Dot 4 fluid - so you're back with a squishy pedal again.

 

Dot 5.1 stuff is the one to use if you don't feel the need for full-on race fluid.

[Colin Mill]

water that un-avoidably enters the braking system

I think this is the big question - how does water enter the system? Even with the brakes off the fluid at the pistons is under a hydrostatic head from the reservoir. So there would only be a pressure trying to push water inwards passed the seals if the car was several feet deep in water! To a lesser extent the same is true of the master cylinder seals. The only other way in for water is via the reservoir - either by leaking in through the cap or by diffusing through the plastic. I don't see the former being likely and the latter only really works if the fluid inside is hygroscopic.

 

If you search the web you will find opinions slagging off Dot 4, DoT5, DoT5.1 and silicone fluids All I can say is that I have used all of them at times - the silicone being used in a Jag for a very long time quite successfully.