Brake fluid?

Hi - replacing brake shoes and bleeding the brakes. What type of brake fluid can I use? Any old Dot3 ok? Or must I find Caster Oil?

Historically, I have always used Castrol LMA brake fluid (since my first MGB in 1973), but in recent times, because I always keep it stocked for the BMWs I work on, I've been using ATE TYPE 200 DOT4 brake fluid.

The "amber" is all that's available now in this country, as the "blue" no longer meets US (over-)regulations__it's the same stuff! Most avid track-types would alternate between the blue and amber fluids, so they could discern thorough brake fluid purging/bleeding. Anyway, it's a premium fluid, without a premium price. Dry boiling point of 536*F, and I haven't experienced any reaction to the rubber seals.

FWIW - in So Cal (drier than back east), I've been using DOT 4 fluid from Napa or AutoZone for years without any ill effects. A quart is in the $6 range. Not a racer, but this stuff works fine driving up and down our local mountains.

Dot 3 or Dot 4 brake fluids are Hygroscopic (absorbing or attracting moisture from the air) Glycol-based fluids and have been reported to absorb water at a rate of approx. 2-3% per year. Although reasonably priced and providing a solid peddle, many manufacturers have suggested a full exchange every 2 years to reduce the possibility of internal system deterioration. Dot 5 is a Silicone-based fluid that is not Hygroscopic and will provide a much extended longevity but is much more expensive and provides a softer peddle.

Since the frequency of my Healey’s use is not uncommon (waiting to be used rather then being used) and since I seem to lack the discipline to do a full fluid replacement every 2 years, I have chosen to use DOT 5 Silicone fluid in my Healey to capitalize on its extended longevity. After a period of 15 years and noticing a small loss of fluid from the reservoir, I decided to do my first fluid exchange and system rebuild. When examining each of the major components, I was delighted to find no internal corrosion or seal deterioration and, although I did do a light honing before seal replacements, question if it was really necessary.

Although there are many positives and negatives to each fluid implementation, I would agree with Randy’s choice of a DOT 4 if I were more discipline at performing periodic fluid exchanges. However, for the many like me, I would suggest considering Dot 5 Silicone fluid as well. Keep in mind that DOT 5 is INCOMPATIBLE with all other fluids and will require a full and careful system flush before changing from any other brake fluid. This can be a major effort for some and would, personally, only consider a Silicone alternative at the time of a full system rebuild. Cost is another drawback with Silicone at prices 3 to 4 times that of conventional brake fluids. However, on the east cost or areas not as dry as Steve’s Ca, I have found it to be worth the cost.

Ray (64BJ8P1)

Randy Forbes said:

The "amber" is all that's available now in this country, as the "blue" no longer meets US (over-)regulations__it's the same stuff! Most avid track-types would alternate between the blue and amber fluids, so they could discern thorough brake fluid purging/bleeding.

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I was quite surprised to read Randy's post and found it a bit hard to believe. Nevertheless after googling "Federal Motor Vehicle Safety Standard brake fluid color" I came to: "49 CFR 571.116 - Standard No. 116; Motor vehicle brake fluids." and there it was!

I have always used ATE's brake fluid in my race cars and, as Randy says, alternating the blue and clear made purging/bleeding an easy task. I suppose I could find a fluid that is the acceptable "clear" in color and alternate it with ATE's amber but I don't like to mix manufacturer's products any more than I have to.

I wonder what ATE used to make the fluid blue? Conventional food colorants are not oil-soluble but several sources supply oil-soluble dies--see: https://www.abbeycolor.com/solvent-dyes.php. Assuming I could get ahold of some of this stuff I wonder how I would determine, other than by trial and error, whether or not it is compatible with brake system components?

In view of his letter to ATE distributors--https://hooniverse.com/2013/08/16/braking-news-ate-super-blue-deemed-illegal-for-us-distribution/--perhaps I need to contact Howard Laster at Continental and see if I can pry some of the confiscated ATE Blue out of his hands if I promise to only use it in my race cars!

Also, glycol-based BF is flammable, silicone is not. It's not common, but there have been instances of glycol BF igniting after a crash and causing the vehicle to burn.

Some Ford Rangers--we have one--caught fire and burned down garages and houses when a short in the switch that shunts cruise control when brakes are applied ignited the BF.

Michael Oritt said:

I was quite surprised to read Randy's post and found it a bit hard to believe....

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Uh huh

Know anybody in Europe? It's still being manufactured, so it's conceivable that someone could obtain it for you__strictly for offroad purposes, of course!

I have some friends in Germany and will ask them to order some and send it to me, assuming sending brake fluid does not violate any Homeland Security regs.

I heard back from Continental and they turned me down on selling me any ATE Blue.

Bob_Spidell said:

Also, glycol-based BF is flammable, silicone is not. ....

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I can tell you from experience that silicone brake fluid burns.

I believe John is correct and from my research DOT 3, DOT 4, and DOT 5 will all burn. Let there be no misunderstanding however. Although the commonly used brake fluids will burn, they are difficult to ignite and are not explosive as is gasoline. So, although brake fluid can be ignited if sprayed onto an open flame, I understand it is extremely rare that this fluid will cause a fire.

Ray (64BJ8P1)

Guys, thanks for all the feedback, really appreciate it. I ended up using DOT3.

Chris