DOT 3 or 5?

Which fluid should I use...DOT 3 or 5. It's a completely rebuilt brake system. After seeing the gunk caused by sitting and DOT 3 I am leaning towards DOT 5/silicone.

I haven't used DOT 5, but pretty much everybody in the zone who has has nothing but praise for it. There was a thread in the past about the pros/cons and what you need to do to run it.

Kaiserjeep/Al switched his over. He also found a cheap source for it in Florida I think. He will chime in with specifics soon.

My MVs all running DOT 5 (silicone) no problems in 18 years.

http://www.collect.com/interest/arti...MV&id=5913

DOT 5 is much better for:
vehicles that sit more/are driven less and definately for vehicles in storage
are exposed to a more humid/water environment...as in the master cylinder has a hole in the cap for venting that lets the atmosphere get in there easily...
vehicles with new brake systems and/or ones in good shape...dont have to worry about changing a bunch of stuff or having a blowout soon and lose some of the higher dollar DOT 5 fluid...it would be much beter to use in a good/new system than an old one that you change a wheel cylinder, then a hose or 2, then the master...etc....
brute4c

Actually, after I did some research, DOT 5.1 is the best. Non silicone.
Water will still get in your brake system, but with silicone not holding onto it, it can and will cause rust, and will cause pockets of water. And water pockets when subjected to high heat, will vaporize. Not good.
Most people, including the military, who use the silicone, tend to flush their systems out on a regular basis.
Will it work. Heck yeah, it works great! It just isn't neccesarily the best for all situations. If you use 5.1 (basically a heat scale of boiling points dry and wet), it has the same boiling points as DOT 5, but isn't silicone.
And besides, honest PMCS will note that you change your brake fluid yearly, so water should be too bad of an issue.
Also, many high quality DOT 4 fluids have the same boiling points as DOT 5, they just don't list it that way because they don't want the confusion.

So Hammer...if its not silicone, what is it? And can it be used in an existing system or does it need either flushing with something like alcohol or replacement of rubber stuff or anything?
Sounds cool to me.....good info.
brute4c

The 5.1 is not silicone. The made the slight number change specifically so it wouldn't be confused with the silicone based DOT 5.
It is compatable with DOT 3 and 4, same base fluid as well.
If you look at the boiling points on brake fluids, you will see which ones are better. Some are listed as DOT 4+, it doesn't really matter as they meet, and exceed the DOT minimum requirements.
As a matter of fact, one of the tricks racers use is their brake fluid is colored either blue or red. And when they flush their system, they use the opposite color from what they are currently running, so they know when they have completely flushed out all of the old fluid.

Yes I am converting my duece to Dot 5. Expensive stuff. I have rebuilt the master,and the hydrovac and installed them. I have 3 of 6 wheel cylinders rebuilt. I hope this weekend I can finish the last three and drive the thing. I'm hoping for a firm high pedal. 14,000 lbs is a good thing to be able to stop. My dot 5 is purple.