What type brake fluid is recommended

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Barry.b

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Hi guys
I am about to bleed my braking system.
I have all new or refurbished components and pipe work, so I have zero fluid in the system currently.
I am not sure what type of brake fluid should I use
Has someone done this recently ?
 
Castrol DOT 4 GT LMA, sold in pint and quart plastic cone top containers, is pretty much the standard. there are others, of course, but DOT 4 is the stuff, not DOT 3, NOT silicone unless you completely clean out the system- not for simply bleeding.
 
If everything in the system is new/replaced, I would consider DOT5. But you would need to check compatibility with the seals in the MC and calipers first (swell check). If it works, it will be the last time you change brake fluid and hopefully you will never have a frozen caliper of corroded MC.

DOT5 has worked very well for many of my friends, and over more than 2 decades.
 
Thanks for the advice guys .
Most of my components came from walloth and nesch
So I am not sure if they are compatible with Dot 5
 
Barry.b said:
compatible with Dot 5
Click to expand...
The only way I know of is to soak a seal in DOT 5 for a week and see if it swells up. On
my XK120, experience has shown that the original Lockheed seals are compatible with DOT5, but most contemporary rebuild seals are not. A set of original Lockheed seals is well over $100 for this era Jaguar, but considering the benefit of no more bi-annual fluid flushes, it seems like a small price to pay if you have multiple old cars.
 
Thanks again guys for all the help !
Does anyone know how much brake fluid a system will take ?
I don’t want to buy too much of it and have it sitting around degrading in my garage afterwards equally I don’t want to find out halfway through the refill that I didn’t buy enough of it .
 
If you have the option to use ATE Blue, then do it and alternate so you know when flushes are complete. Blue is not available in the US anymore because of.......stupidity of the DOT.
 
This was in my trunk when I bought my car in late '80s :

tempImageOr2jO5.png
 
Here is my experience with DOT 5. I used it in my 1973 FJ55 Landcruiser. Before I used it, I had to rebuild or replace at least 2 wheel cylinders every year due to corrosion. I used it primarily off-road and water crossings were done occasionally.

Before I filed and bled with DOT 5, I replaced all of the rubber components in the hydraulic system and flushed it with ethanol, followed by blowing out with air. I never had any problems with the brakes system after that.

I was so happy with the results that I tried DOT 5 in my race car. That was a disaster. After about 3 or 4 laps the pedal got soft and had to be pumped to get them to work. I tried bleeding several times thinking there was still some air in the system but got no improvement.

I did some research online to find out more about DOT 5. It seems that it aerates easily and forms very small bubbles which compress when using the brakes. I came to the conclusion that in a race car, these fine bubbles form from using the brakes a lot, flowing fast back and forth through the hydraulics and getting hot. I went back to using high temperature racing brake fluid and flushing periodically.

I use Motul 600 in my race car but don't recommend it for a street car unless you want to bleed often. The chemical fluids used in race brake fluid will take higher temperatures, but also typically absorbs moisture quicker than standard DOT 4. I know there are some that say they absorb moisture slowly, but I don't trust that. I use any good brand name synthetic DOT 4 brake fluid in all my vehicles other than my race car.
 
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Yeah, I've heard that early FJs had water issues and needed wheel cylinder rebuilds relatively often - a cousin had one.

Aeration in your race car - seems odd. Aeration should only happen if there was air in the system to be mixed with, and the only free surface (air/fluid interface) would seem to be in the master cylinder reservoir, where the exchange between the amount in the reservoir and amount in the lines is greatly disproportional. Simply "fast flow" shouldn't cause bubbles until you get into cavitation - which you shouldn't - and in which situation the bubbles collapse readily when conditions change.
 
I agree with you on the aeration. I thought the same thing when I kept bleeding it to try to get it to work. Someone pointed out that the DOT 5 fluid must be poured very slow, or this fine aeration can occur. It may also occur when the fluid is originally filling the brake lines. All I know for sure is, it would not work with my race car.

I never had this issue with my FJ55, but the brakes did not see the activity of my race car. I understand DOT 5 is more compressible than DOT 3 or 4, but I could not tell any difference in the FJ55. I guess it is possible the heat in the race care brake system makes the compressibility worse, but having to pump the brakes to get them to work is mainly a symptom of air in the system.
 
I have used Red Line RL-600 synthetic DOT 4 after both a master cylinder replacement and after front caliper replacements. No problems and a complete flush both times. 3X16 oz bottles each time.
 
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