The only place for a coil spring is up Zebedee's
Joined: Oct 20 2018
Posts: 166

Has anyone used silicone brake fluid or have any views on its benefits/disadvantages?

Joined: Apr 23 2019
Posts: 581

I'm usually one for listening to the manual, but the write up on the silicone stuff is quite intriguing. I guess I'd have some concern about flushing all the old brake fluid out first - on the other hand your system is almost all new anyway, right?

Joined: Sep 02 2016
Posts: 515

Intriguing indeed....


Looks like the main advantage of Silicone is that it does not dissolve (cellulose) paint..
but the disadvantage is it allows water to 'pool' (and corrode Master Cylinders etc) ?

-Based on that I'm sticking with stock !

Joined: Oct 20 2018
Posts: 166

Thanks both.

Yes, Rob there might be a bit left in the booster and pump which are still original but everything else is new.

Interesting article Dave, I'll probably stick with conventional.

Joined: Jun 17 2018
Posts: 786

Brake fluid doesn't effect clear coated paint, only singe stage..

Joined: Jan 16 2016
Posts: 433

Silicone brake fluid is non hygroscopic, in other words it does not absorb moisture from the air, one of the main reasons for brake failure.
It is used in race cars and can be used in brakes that run at very high temperatures. I don't think you have to change it either.
Disadvantages, as far as I know? Expense. Doesn't mix with normal brake fluid.

Joined: Sep 14 2016
Posts: 520

Silicone brake fluids were originally developed in the USA for military vehicles. Primarily to allow vehicles to be taken straight from storage and into battlefield service without a regular fluid change cycle on stored vehicles. En-mass fluid change on a battalions worth of transport before deployment being a right PIA and major league difficult on many AFVs. Lower freezing point is handy on air deployments too. Cargo aircraft get cold inside.

It has absolutely no advantages whatsoever in a normal vehicle. It may not be actively hydroscopic but it still entrains water via temperature cycling and similar drivers. Objectively it should only be used in a sealed or semi sealed system. Preferably in a pump fed system with arrangements to extract any entrained water. Our P38s would be a good candidate if fitted with a motorcycle style fexible diaphragm sealed reservoir. Theoretically motorcycle systems can safely use silicone fluids. In practice temperature cycling seems to cause water ingress through the seals and promote corrosion inside.

The Australian Army had some research done into best ways of changing from the normal issue fluid to silicone fluids. With sometimes worrisome results

"In the case of vehicle 37-971, total loss of braking effect and loss of pedal resistance was noted approximately 15 minutes after the vehicle had been returned to the garage. Next day the brakes had returned to normal with no sign of fluid loss or leakage from the system. All brake assemblies were stripped from this vehicle with the liquid contents intact and taken to MRL for disassembly and inspection. All were found to contain residues of OX(Aust.)8 despite the syringe sampling operation which had resulted in the samples to which Table 1 refers."

Full report is at (https://apps.dtic.mil/dtic/tr/fulltext/u2/a159501.pdf). Looks like the experimenters were more careful than an ordinary mechanic.


Joined: Oct 20 2018
Posts: 166

As always Clive, comprehensive and factual. Many thanks.

Joined: Feb 25 2020
Posts: 255

Great information, did not know that ... thanks!!