Hot Rods brake fluid

IS THERE ANY SIMPLE WAY 2 TELL IF U HAVE DOT 3 OR 4 - OR SIMPLY 5 IN YOUR EXISTING BRAKE SYSTEM WITHOUT A CHEMICAL ANALYSIS ???

 

Unscientific way is DOT 3 and DOT 4 will ruin paint.........

 

The silicone DOT 5 I have used is colored purple.

 

Take a small amount of what you have in the master and mix it in a glass with dot 5 in it. If it looks like salad dressing and doesnt mix you have dot 3.

 

DOT 3 and 4 are compatible. Just don't mix any DOT 5 in it.
You probably already know this.

 

Count the dots!
Seriously, take a syringe and suck out whats in the MC reservoir and add what you want. You might add "the new stuff" and repeat as above then go forward with the new juice...just saying!

 

DO NOT do this! If it has DOT 5 and you add 3 or 4 (or vice versa) the remaining fluid in the limes and calipers/wheel cylinders will not mix and they will at minimum become gummy and loss of brakes is eminent. Really bad idea.

 

Take the car to a service center like Jiffy Lube and have the brake system flushed and filled with the type fluid you choose. They will generally charge about $100.

 

DOT 3,4 and 5 have progressively higher BP's. Look them up if you want to check using the BP
method.
Since DOT 3 and 4 are compatible, no problem. They are also good absorbents for water. DOT 5
is not miscible with water which is its disadvantage. Sample some of you MC fluid and add
a small amount of water in a transparent container....watch the interface layer. If it the layers stay separate, its DOT 5

 

I usually go with these dots

 

3, 4 and 5.1 are the same type, but 5 is some synthetic silicon stuff that doesn't damage paint, but DOES eat rubber.

God only know why they numbered 5.1 like that. I bought some for my Sportster, after the store dork told me "It is virtually the same as 5". No, dork, it is totally different.

 

DOT 5.1 has a 10*C higher BP than DOT 5.....apparently numbered solely based on BP

 

So why not DOT 3, then DOT 3.1?

 

Do you have any PROOF that this is true?

I have proof that this is NOT true. I poured some 3 and some 5 into a container and have been watching it since Christmas. No gummy yet!

 

This is DOT 5s advantage! Not disadvantage

 

Miscible ? At 71 yrs old that's a first for me.

 

think of it as mixable but misspelled

 

I use 5 in all my project cars, have for years. Have always put it in from an empty system. Works well, doesn't affect paint, which is why I use it. Never had any rubber failures with it.

 

DOT 3, 4 and 5.1 are specifically intended to absorb water. Since the MC breaths atmospheric air
laden w/ varying amounts of water, unabsorbed water is now susceptible to freezing in cold
winter months.