Author Topic: Silicone brake fluid.  (Read 1960 times)

Bob Purton

  • Prolific Poster
  • *****
  • Posts: 5041
    • Inter microcar
Silicone brake fluid.
« on: May 15, 2015, 09:15:53 AM »
As we touched on this subject in a different thread I thought it might be an interesting topic to research and discuss as many microcars are left standing for long periods it could be advantageous for some.
I have never tried it , Dave had a negative experience although it wasnt he personally that filled the cars he bought with the DOT 5. Apparently ridding every trace of the other stuff is vital as the dot 5 will gather these traces up into globules and they will cause severe problems.
Has anyone else used it and what experiences did you have?
Looking it up on line it appears to be quite a controversial subject! ;D

I found this ....
"A newly rebuilt and scrupulously clean brake system filled with silicone fluid should outlast a system filled with glycol fluid by several times. There is little advantage in adding silicone fluid to a system which contains even small amounts of contaminants. Merely bleeding the system is not enough, as there will be pockets of old fluid and sludge which will not bleed out. Silicone fluid tends to concentrate any residual glycol fluid, moisture and sludge, into slugs, instead of allowing their dispersal throughout the fluid, as does glycol fluid. This can lead to relatively severe but localized problems, rather than the more general system deterioration experienced with old moisture-laden glycol fluids. This may be a factor in reports of leakage when silicone fluid is used in non-rebuilt systems which had been used with glycol fluid. A "new" system full of silicone fluid will require very little maintenance for years."


  • Quite Chatty
  • ****
  • Posts: 402
Re: Silicone brake fluid.
« Reply #1 on: May 16, 2015, 07:31:02 AM »
From my own research-


1. In theory should last for the life of the vehicle, and doesn't degrade over time e.g. non-hygroscopic

2. Doesn't damage paint.


1. Much more difficult to purge air from the system, resulting in a spongier feel to the brakes. Pressure fed bleeding system sounds pretty much essential.

2. Moisture will pool up and gather at the lowest point- water being more dense than silicone oil.

1959 LHD 3-wheel Isetta.