Does anyone recommend Dot5 Silicone based brake fluid?

[lloyd]

Noting a slave cylinder question, made me wonder about Dot5 Silicone brake fluid and specifically, its use with our not-so-new vehicles.

I have no personal experience with this "newer" brake fluid. I am aware that it is not a good thing to mix the two fluid types and that flushing the system is recommended before using Dot5 in a system previously filled with Dot 3-4.

The few times the subject has been raised, I have heard how Dot5 "allegedly" provides a "mushy pedal" and because it does not absorb moisture, the water settles in the system and may promote internal corrosion. But none of these naysayers have actually tried the product.

Dot5 seems to be sold everywhere. Some people must be using it, so I assume it has it proponents. Can someone on this board offer some real life experience with the use of this product? Is it as bad as its critics claim, or just an old wive's tail?

Thanks in advance.

 

[jmackro]

I have used silicone brake fluid

I use silicone fluid in my '63 Alfa Romeo Giulia spider. Have had it in there since I restored it 15 years or so back (well, I've changed it a few times over that period). It works fine.

My reason for using it in that car is that I dislike the "paint removal feature" of Dot 3 & 4 fluids. The Alfa is nicely restored, and I don't want the firewall paint bubbling around the reservoir.

For a competition car, silicone is not the best solution, as I believe it boils at a lower temperature than Dot 3 or 4. For street use, I doubt you would encounter any problems.

My understanding is that you can't just bleed out the old Dot <5 fluid, and refill with Dot 5. Instead, you need to rebuild all the hydraulics, and blow out the lines before switching from/to silicone. There are tales of rubber parts swelling when the type of fluid is changed, though I have no personal experience with this happening.