Thread: Whats this, Dot 3 silicone

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What happened to the regular stuff? I only found the silicone stuff at the parts store. Is this suff any good?

Originally Posted by BigTruckDriver

What happened to the regular stuff? I only found the silicone stuff at the parts store. Is this suff any good?

Someone locally must have the glycol based fluid -

Silicone CANNOT be mixed with regular fluid. It will swell any and all rubber seals and piston cups plus turn any rubber hoses to mush. It will slightly compress leaving you with a spongier pedal then you had before. To use any silicone fluid, you have to change EVERY piece of rubber (neoprene), including rebuilding your MC and wheel cylinders with all new innards, in your system, flush the lines with LOTS of alcohol. It would probably be best to replace the MC and WCs and/or calipers as it is extremely hard to get all of the glycol based fluid out of a rough casting such as a MC.

Now to answer your question - yes, it is good stuff but it has limitations and IMO, is for racing or for those 'special' cars that are driven only a few times a year as it doesn't destroy paint and doesn't absorb moisture and therefore rust the hydraulic lines plus it usually has a higher boiling point then glycol based stuff.

I used it in a street rod and it was a study in frustration with crappy brakes. I finally rebuilt everything, including all new cylinders and finally had good brakes. Others have used it and love it - but it should only be for a brand new system that has never had glycol based fluid.

Oppps I meant sythetic Dot 3, I have been reading up and got the synthic confused with the silicone. Is this sythetic dot 3 better or is the original dot 3 better?

So I can flush my brake system with alchohol? i have a 89 suburban and I am trying to get better brakes . I noticed that the brake fluid is DIRTY!!!! ,not even funny, its bad. I have some stainless lines coming some time this week and going to replace the pads with better ones.

Originally Posted by BigTruckDriver

Oppps I meant sythetic Dot 3, I have been reading up and got the synthic confused with the silicone. Is this sythetic dot 3 better or is the original dot 3 better?

I guess I'd see if they had a web site - possibly wont absorb as much water and may have a higher boiling point. The syn stuff should be ok but I sure would do some on-line research.

What about flushing the system with alcohol ? Whats the procedure?

Originally Posted by BigTruckDriver

What about flushing the system with alcohol ? Whats the procedure?

Unless you were going to "try" silicone, for the most part just a flush with regular fluid should do a sufficiant cleanup of the old fluid. Either way, take a turkey baster, suck out the MC brake fluid and fill it with fresh then bleed the system - just make sure you don't pump the brakes without any fluid in the MC or it will just take a bit longer. You can get different color fluids to tell when the new stuff is coming thru. When I do it, I go around each of the bleeders at least 3 times just to make sure - but it is messy even with a hose and catch can. An alternate way as long as the MC is above the brake cylinders or calipers is to gravity bleed them thru a clear hose into a clear bottle with a bit of fluid in the bottom covering the end of the hose - but just don't expect to do it in a hurry - like hours. Then you have to do at least one pressure or pump and hold bleed. Or if you have a MityVac pump you can try to suck it out, but I have never had much luck with mine

JUST DON'T SPILL ANY OF THE FLUID - OLD OR NEW ON YOUR PAINT AS IT WILL ALMOST INSTANTANEOUSLY GO THRU IT TO BARE METAL

Did the info sheet happen to mention if the synthetic DOT 3 is harmful to paint?

And if it's hygroscopic (water attracting) like regular brake fluid?

Price comparison with the regular stuff?

The paint damage bit the reason I went with silicon in my 32.
The pedal is a touch softer, but not a whole lot.
It's been in the car since 93 and still works fine.

Topped it off twice in that time period.

Me too. I've used silicone since about 1989, and love it. That's what is going into my current Tand all cars beyond. But, as mentioned, I started off with a clean system, with no mixing.

Don

I am still wanting to flush the system with alcohol. My brake fluid is very dark ( I dont drive it often) and would like to clear the entire system. What do I do just pour it down the pipes and pump like crazy,lol? I am also reading that I can go to DOT 4 since it has the same properties but with a higher boiling point?

BG makes a synthetic Dot 4 that is compatible with all systems (minus the newest silicone Dot 5 they also cover that with another syn/sil product). Use the standard bleeding and flushing approach (or have the shop with their system do it with their machine) and run it. I do not work for them, I just have had a solid success rate of over 30 years of their products and trust it. It has your anti boil characteristics and good hydraulic hold where some others will go spongy. It does not swell or deteriorate the soft products in your system. Standard proceedure is to drain with a suction bulb or other device to empty the resivior and refill it with the new syn and complete the bleeding process until clear. Better brakes and better stopping when coming down hill or towing.

And I Repeat - Just Don't Mix Silicone And Glycol Based Fluid Without A total Major Brake System Overhaul And Cleanup.:cry: