Braake fluid

[drezin]

How do you tell if brake fluid in a car is Dot3 or Dot 5

 

[slowforty]

silicone should be purple in color

 

[Mart]

Take a small sample and drop it into water. Dot 3 will mix, dot 5 will not.

Disclaimer: Haven't tried it, but I did read that somewhere.

From personal experience I can say that dot 4 is better than dot 3. (If you don't want silicone).

Mart.

 

[Lanny]

How do you tell if brake fluid in a car is Dot3 or Dot 5

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Now there is a Dot 5.1 also. It is glycol based just like Dot 3 and 4, and
they can all be mixed together without causing any harm.

Dot 5 brake fluid is silicone based and should Not be mixed with any of
the glycol based brake fluids, in fact, it will Not mix together with glycol.

As Mart said, put a couple drops is a little water and try to stir it up
and any Dot 5 silicone will separate pretty quickly.




.

 

[Aarongriffey]

I replaced all five brake cylinders on my F-1 in January 2000. I used dot5.
When do I need to flush the system again? Is 20 years long enough or doesn’t it need to be changed?

 

[Frank Miller]

If it does not tell you on the can it is in, throw it away.

 

[V8COOPMAN]

How do you tell if brake fluid in a car is Dot3 or Dot 5

If it does not tell you on the can it is in, throw it away.

If the fluid is already in the car, the can is likely AWOL! DD

 

[51 MERC-CT]

I replaced all five brake cylinders on my F-1 in January 2000. I used dot5.
When do I need to flush the system again? Is 20 years long enough or doesn’t it need to be changed?

Seeing that you essentially started with a new system before installing DOT5,
all indications I have seen is that it does not have to be changed with normal use. DOT5 is not hydroscopic (does not retain moisture ) This is the main reason for changing from DOT3 etc.

Flushing a system that is currently using DOT3 with alcohol etc. can damage the rubber components and after running DOT5 for a period of time, the rubber starts to deteriorate and leak. Then what gets erroneously blamed for the failure? DOT5!!

I have had DOT5 in my system for over 25 years with no strange discoloration and moisture levels acceptable.

 

[tubman]

I have an electronic device that "reads" the moisture content of DOT3/4 brake fluid. I use it on all of my cars, and have found that DOT3/4 fluid does not approach the "Warning" level on the tester unless it has been in use for at least 10 years. That is based on the fact that our cars are almost always stored under favorable conditions, which should lead to increased life for all components.

How many 20-30 years old cars are out there running the original brake fluid from the factory? When was the last time you drained/flushed/changed the brake fluid on your daily driver? It is also interesting to note that (at least in the USA), I know of no government mandate for changing brake fluid after X years or Y miles. This tells me that brake fluid has a long effective life.

As to DOT5, I had it in a Corvette for almost 30 years with no problem. Learning what I have about the longevity of DOT3/4, I'll never use DOT5 again because it was almost impossible to get the system bled correctly. Bottom line? The effective life of DOT5 (especially in a pampered collector car) is unknown. If I had to guess, I'd say you're good for another 20 years.