I was looking into changing the fluid from DOT 3 to 5 and was calling around to see who sold it and for how much and I was told that if I change a DOT 3 or 4 system to 5 that I need to clean out the entire system with Iso Alcohol before I changed the fluid out....has anyone else heard this? is it really necessary? and would you also do this for the clutch line? i'm going to use the 5 in the clutch too so I dont have to keep two kinds of fluid around. anyone help me out here?

 

Why do you want DOT5? It is incompatible with DOT 3/4. Just get a high quality DOT4 and be done with it. DOT 5.1 is also ok, it is basically a high-quality version of DOT4.

 

Just use Dot 3 and forget about it.

 

well it was suggested to me by a former county sherrif who has on more than one occasion boiled the DOT 3 fluid in a patrol car in less than ten minutes of extreme driving, he suggested that if I want to do any kind of road racing activity that I should bump up to at least a dot 5.....now does somebody know something about this?

 

dot 5 is no good with abs and may rust your brake components because it does not absorb mosture like 3 and 4. Upgrade to a good dot4 and flush yearly.

 

may rust my components? thanks i'll look more into that.

 

found this in case anyone else was thinking about this, i was wrong its 5.1 that I would be putting in fluid info

 

Lol, re-read my first post then. ATE Superblue is a popular choice around here, and Valvoline synthetic is a cheaper alternative that should be more affordable. I have ATE Superblue because blue brake / clutch fluid is cool-looking

 

heh, didnt mean to sluff off what you were saying, thats part of why I would be getting it also the added safety of not boiling my brakes when I hit it hardcore....as i occasionally do..

 

occasional hard braking won't do it....even autocrossing probably wouldn't....you need to be on a race track to trash fluid. even then, its the pads that will cause fade before the fluid.

5.1 stuff was developed for the military and RV industry, i believe its silicone based....it can sit for long periods and won't absorb water.....it will have a spongy feel, and I would avoid it.

use dot 4 and bleed some fresh fluid through after a weekend racing event. I raced motorcycles for 3 years...and dot 4 was what we used, with frequent bleeding.

 

Geez.

DOT 5
DOT5 brake fluid is also known as "silicone" brake fluid.

Advantages:

DOT5 doesn't eat paint.
DOT5 does not absorb water and may be useful where water absorption is a problem.
DOT5 is compatible with all rubber formulations. (See more on this under disadvantages, below.)

Disadvantages:

DOT5 does NOT mix with DOT3, DOT4 or DOT5.1. Most reported problems with DOT5 are probably due to some
degree of mixing with other fluid types. The best way to convert to DOT5 is to totally rebuild the hydraulic
system.
Reports of DOT5 causing premature failure of rubber brake parts were more common with early DOT5
formulations. This is thought to be due to improper addition of swelling agents and has been fixed in recent
formulations.
Since DOT5 does not absorb water, any moisture in the hydraulic system will "puddle" in one place. This can
cause localized corrosion in the hydraulics.
Careful bleeding is required to get all of the air out of the system. Small bubbles can form in the fluid that will form
large bubbles over time. It may be necessary to do a series of bleeds.
DOT5 is slightly compressible (giving a very slightly soft pedal), and has a lower boiling point than DOT4.
DOT5 is about twice as expensive as DOT4 fluid. It is also difficult to find, generally only available at selected
auto parts stores.


DOT 5.1

DOT5.1 is a relatively new brake fluid that is causing no end of confusion amongst mechanics. The DOT could avoid a
lot of confusion by giving this new fluid a different designation. The 5.1 designation could lead one to believe that it's a
modification of silicone-based DOT 5 brake fluid. Calling it 4.1 or 6 might have been more appropriate since it's a
glycol-based fluid like the DOT 3 and 4 types, not silicone-based like DOT 5 fluid.

As far as the basic behavior of 5.1 fluids, they are much like "high performance" DOT4 fluids, rather than traditional
DOT5 brake fluids.

Advantages:

DOT5.1 provides superior performance over the other brake fluids discussed here. It has a higher boiling point,
either dry or wet, than DOT 3 or 4. In fact, its dry boiling point (about 275 degrees C) is almost as high as racing
fluid (about 300 degrees C) and 5.1's wet boiling point (about 175 to 200 degrees C) is naturally much higher
than racing's (about 145 C).
DOT5.1 is said to be compatible with all rubber formulations.

Disadvantages:

DOT5.1 fluids (and Spectro's Supreme DOT4) are non-silicone fluids and will absorb water.
DOT5.1 fluids, like DOT3 & DOT4 will eat paint.
DOT 5.1 fluids are difficult to find for sale, typically at very few auto parts stores, mostly limited to "speed shops."
DOT 5.1 will be more expensive than DOT3 or DOT4, and more difficult to find.

 

opps mixed those up...good catch.

i think the answer is still to stick to a quality Dot 4 fluid....

 

Here in Norway they haven't sold DOT 3 in ages..... i've heard someone say that the European Union does not approve DOT 3 anymore because of it's low boiling point. However I don't know if that is true or not...
If you're "lucky" you might find DOT 4, but almost everything they sell these days over here is DOT 5.1....
I've been using 5.1 all the time, never any problems or boiling....
And you don't have to flush the system with alcohol before putting in 5.1

Just NEVER use DOT 5!!!