The Stovebolt Site Forums The Shop Area Driveline Should I use silicone brake fluid in rebuilt system

I 've totally rebuilt my brake system from the master cylinder all lines and all four wheels clays. A new material. Should I use dot 4 silicone fluid to reduce moisture issues

Type silicone brake fluid into the Stovebolt Site Search and you will find dozens of comments on the subject.
Harold

Silicone fluid is Dot 5, Dot 4 is just the latest version of the older fluid. On that note, mine has had Dot 5 in it for 15 years without any problem. I never tried any other fluid so I cannot say where the pedal requires more effort or not. I have read dozens of such stories about the fluid not working in older cars and trucks and all the problems folks have had with it, but mine works just fine for me. On the plus side, Dot 5 will not harm paint if thats something you are concerned with.

Joe

Been using Dot 5 in my 39 for many, many years. Never had an issue with it. Since all of your brake components have been replaced, you wouldn't have to worry about contamination problems.

Rick

If you do use DOT 5 silicone, you will need to be 100% certain that the rubber components are compatible with it. Many direct oem replacement components are not, as they are intended for use with glycol based fluids that are the oem spec. If the rubber components are not silicone fluid compatible, the fluid will damage them, found that out the hard way. In addition, silicone brake fluid is more difficult to get all the air bled out of the system, due to the nature of the fluid. In addition, due to the non hydroscopic nature of silicone fluid, any moisture that gets in the system due to the vented master cylinder will settle in the bottom of the master and wheel cylinders, rather than getting absorbed by the fluid. This can lead to damage in the master and wheel cylinder bores. Again, learned that the hard way. Personally, I would suggest using the oem spec glycol based fluid and do the annual system flushes as noted in the owners and shop manuals and leave the silicone fluids for vehicles that use them as oem fill.

I've been using the Valvoline Synthetic brake fluid for years. No problems...at least no in my lifetime.

I use DOT 5 but not because its better, but ONLY because I do not want to re-do the paint job on the frame every time I get a leak. If regular fluid wasn't also paint remover, I would go with DOT3. So far no leaks, but I haven't gone anywhere yet either.