Dot 5.1 brake fluid?

Digitalchaos

Registered User
Has anyone ever heard of this DOT 5.1 brake fluid?

It is apparently non synthetic like Dot 3 & 4, therefore seems compatible with these fluids. It also has a higher wet and dry boiling point, implying better performance.

Has anyone used this, and what can you say about it?
 
dot 5 brake fluid

yes i've heard of it i believe its a silicone base fluid but not sure if its compatable with dot3 i would do some homework before using it..............Doug
 
DOT 5.1 is glycol based like DOT 3 & 4 but has higher boiling points when both dry and wet. It also has a higher dry boiling points than DOT 5 which is silicone based.

Bel-Ray has a good faq on brake fluid.

http://www.belray.com/consumer/Q&A pages/q&abf.html

And here is an entry from google

http://groups.google.com/groups?hl=...BanL8.71175$9z5.4648556@typhoon.austin.rr.com

In general what I found is that while 5.1 is compatible with DOT 3 and 4, it's main advantage is that it has a substantially higher boiling point when both wet and dry. This is why you'll see it used in road racing quite a bit.

One question I couldn't find an answer to is it's lubricity. Because we have ABS, the lubrication qualities of the fluid are very important. So I would stick to the stock fluid unless you are going to road race or can track down specifics on it's compatibility with ABS system.s
 
From what I can remember dot 5 was made for special usage as in vetts and vipers and is not compatable with dot 3-4. Dot 4 was made for cars that sit alot like old musle cars and antiques. Dot 3 is the standard.
 
DOT 5.1

advantages

high performance, higher boiling point either dry or wet than DOT 3 and DOT 4, (act boil pt is around 275*C dry, 200*C wet)

compatible with all rubber formulations

disad's:

non silicone, will absorb water (which could almost be thought of as an advantage because the silicone DOT 5 fluid puddles water in one place since it does not absorb water... no puddles with 5.1)(of course any water is bad because it causes corrosion.. )

will eat paint, (same as DOT 3 & 4, so nothing out of the ordinary)

difficult to find and expensive, usually only found at speed shops



I'd go with DOT 5.1, seems like it's better for performance applications and should work with DOT 4 if you need some fluid in a hurry due to being a non-silicone.

Silicone seems like high maintenance, hard to find, and doesn't mix with other brake fluid. Also gives a softer pedal feel since it's compressible, and has lower boiling point than DOT 4

EDIT: after re- reading the thread..

DOT 5 and DOT 5.1 are two seperate kinds of fluids..

DOT 5 is silicone, he is asking about 5.1, which is non-silicone.

DOT 5.1 has nothing to do with DOT 5, DOT 5.1 is like DOT 3 and DOT 4.. DOT 5 is not compatible with any of the rest since it is silicone.
 
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Thanks for the excellent information everyone. It seems likely then that I will attempt to find & try 5.1, or at least use Dot 4 for the higher boiling points. I believe the system currently houses DOT 3, though I could be wrong.

Thanks again.
 
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