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Dot 5 brake fluid = bad?

Discussion in 'Wheels / Suspension / Tires / Brakes' started by CrazyAzn, Aug 15, 2006.

  1. CrazyAzn

    CrazyAzn Senior Member

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    well a friend of mine sent me this:

    a former materials engineering supervisor at a major automotive brake system supplier, I feel both qualified and obligated to inject some material science facts into the murky debate about DOT 5 verses DOT 3-4 brake fluids. The important technical issues governing the use of a particular specification brake fluid are as follows:

    1. Fluid compatibility with the brake system rubber, plastic and metal components.
    2. Water absorption and corrosion.
    3. Fluid boiling point and other physical characteristics.
    4. Brake system contamination and sludging.

    Brake system materials must be compatible with the system fluid. Compatibility is determined by chemistry, and no amount of advertising, wishful thinking or rationalizing can change the science of chemical compatibility. Both DOT 3-4 and DOT 5 fluids are compatible with most brake system materials except in the case some silicone rubber external components such as caliper piston boots, which are attacked by silicon fluids and greases.

    DOT 5 in its pure state offers a higher boiling point (500F) however if water got into the system, and a big globule found its way into a caliper, the water would start to boil at 212F causing a vapor lock condition [possible brake failure -ed.].

    from the Airheads BMW Club newsletter - July 1995

    my questions is, is dot 5 bad? my friend brought this to my attention and am wondering the same question myself. . . if anyone could clear this up for me it would be great.

    thanks
     
  2. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    sounds right to me. i do know that dot5 shouldnt be used in regular brake system. the explination above seems very familiar.
     
  3. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Yup, no DOT5 unless your brakes are designed for it. The metal parts of your system shouldn't care what DOT fluid you have, but the rubber parts do- and DOT5 sucks up water like nobody's business.
     
  4. phyregod

    phyregod !!YTINASNI

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    Dot 5 is synthetic.. which is trash. Get dot 4 in non synthetic ftw!
     
  5. MikeBergy

    MikeBergy Blah blah blah....

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    no complaints about my synthetic DOT 3/4 fluid... :shrug:
     
  6. pissedoffsol

    pissedoffsol RETIRED

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  7. MikeBergy

    MikeBergy Blah blah blah....

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    that stuff is expensive. I have yet to see one instance of where I actually needed that kind of fluid performance. I guess I'll find out in december.
     
  8. E_SolSi

    E_SolSi Member of the 20 nut club Moderator VIP

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    smurff jizz isnt that expensive
    $10-16 per quart and it only takes about half a quart to do your whole brake system
    so based on a yearly flush through it will cost you $5-8 per year to use smurf jizz
    i hardly think thats expensive
    i waste more than that every day on shit i cant even remember

    even if you only run it as insurance in the rare instance that you MIGHT need the added temp resistance $5-8 is pretty damn cheap if you ask me
     
  9. S2k Awe

    S2k Awe Junior Member

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    I like ATE Super Blue & Type 200. Same fluid, different colors, helps you know when you've flushed completly :)
     
  10. E_SolSi

    E_SolSi Member of the 20 nut club Moderator VIP

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    yep the blue is the "smurf jizz" we are talking about
    excelent stuff
    i have no complaints about it and it has stood up to all of the abuse ive put it through
     
  11. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    where do you buy it?
     
  12. MikeBergy

    MikeBergy Blah blah blah....

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    I remember seeing it cost more than that...hmm... must've been someone trying to rip people off then. I coulda sworn it was like 15$ for the little bottle, what is it, a pint?

    Ian: Google is your friend...
    Discount Super Blue Brake Fluid / ATE TYP 200 / SuperBlue - RaceShopper.com
    ATE Super Blue Racing Brake Fluid
    Turner Motorsport: Product ATESB
    Amazon.com: ATE Super Blue Racing Brake Fluid Dot 4: Automotive
    LOL, you can even buy it on Amazon!!!
     
    Last edited: Aug 17, 2006
  13. CrazyAzn

    CrazyAzn Senior Member

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    im using some valvoline syn that exceedes dot3/4 standards. it has a boiling point of like 500F, which is pretty good in my opinion. . . but it was a bitch and some to bleed out the dot5 shit i put in -_-. . . live and learn i guess
     
  14. jazzop

    jazzop Junior Member

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    OK, folks, let's look at each of the above 4 items.

    1. The critical item here is RUBBER. All brake fluids available today are compatible with every metal and plastic used in automotive brake systems since WWII. But natural rubber is a bitch. Anything other than silicone (aka DOT 5) brake fluid will eat away at natural rubber brake components (seals, boots, etc.). Guess what, Honda folks.... your brake systems do not contain natural rubber! In fact, natural rubber has not been part of the brake system of any car built after, say 1970 or so (I'm sure there are the rare exceptions, but let's agree that your Honda does NOT have natural rubber brake components, ok?). The bottom line is that if you are running a car under 30 years old, you may feel free to use ANY brake fluid you choose, from an equipment compatibility standpoint.

    2. DOT 5 Silicone fluid is the only brake fluid that does NOT absorb water. This is good and bad. If your brake system has been properly filled with 100% (not 99.5%) DOT 5 and properly bled (remember, air contains water), then you should be fine. But since most people like to cut corners, any mixture of glycol-based (DOT 3 or 4 or 5.1) brake fluids will quickly absorb that water and create bubbles that will, when the car sits, rust out your brake lines from the inside; and, when the car drives hard, possible cause a "vapor-lock" style brake failure.

    On the other hand, you could fill up your system with a glycol-based fluid, forget the silicone, and be just fine with whatever small amount of moisture happened to be in the lines, since it would dissolve throughout the whole system of fluid and only pose a problem if the proportion of water rose too high.

    3. Boiling point is only an issue for high-performance applications. Yes, DOT 5 has a higher b.p. than DOT 3 or 4, but its quirky properties make it not suitable for most people. No offense intended, but I don't think the average rice boy has the attention to detail required to run a car with silicone fluid. Use DOT 4 Castrol GT/LMA. It's by far the best performance to forgiveness trade-off.

    4. Contamination and sludging is going to be dependent on how well one flushes and maintains the system, not the fluid one uses. But as I said before, silicone fluid-- if allowed to mix with water-- will put all that water in one place in your system and potentially cause corrosion from the inside.

    The quote in the OP had some crazy statement about how silicone rubber parts "are attacked by silicon [sic] fluids." This is ridiculous. Silicone (which is not the same a "silicon") brake fluid is like Johnson's Baby Shampoo. It doesn't corrode anything, much less something else made of silicone. It's the only brake fluid that won't eat your paint if you happen to spill some.



    Hope this helps
     
  15. CrazyAzn

    CrazyAzn Senior Member

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    that was interesting, thanks again dude makes me feel a slightly better. even though i already drained all the fluid from my car. But like i siad thanks for the info dude, its much appreicated.
     
  16. TurboMirage

    TurboMirage YEEAAAHHH VIP

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  17. phyregod

    phyregod !!YTINASNI

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  18. jazzop

    jazzop Junior Member

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    Yes, maybe it's a bit of a rant. I own two classic British cars, and silicone brake fluid is a common issue in the old Brit car world. But it shouldn't even cross the minds of people who work with modern cars.

    What's next? Someone starting a thread about converting their ignition system to magnetos because they don't require a battery or alternator?
     
  19. CrazyAzn

    CrazyAzn Senior Member

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    HAHA, thats halarious. . . .
     
  20. Hondahappy

    Hondahappy New Member

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    Hello and Welcome to All Honda People. I am new here and hope you will welcome me into your forum. Hope also to be an asset to everybody on the Honda Forum. Concerning silicone DOT 5 brake fluid, I first became accustomed to the fluid in the antique car hobby. It has disadvantages and advantages. Disadvantages I have understood is it is more difficult to find, more expensive and is not at all compatible to DOT 3 standard brake fluid, meaning it does not mix. We used silicone brake fluid over regular standard brake fluid, because it will not harm the paint on your car. It is much more gentle with internal brake system parts, has a higher boiling point and works well. One of the big downsides is hydrate retention, meaning it us a water magnet. As long as you keep the system sealed and in proper working order, this shouldn't create an issue. Key is changing fluid every 50,000 miles. We are super careful when servicing our brakes, but when bleeding calipers sometimes fluid is released around the master cylinder reservoir area, creating a mess. Standard brake fluid is hades on painted surfaces. Anyway I do realize we all have different opinions about our preferences and what we like to use. Off topic is the reason it became imperative to use is old vintage automobile brake systems are difficult to find parts for and to find a fluid which is harmless to a brake system's internal parts appealed to me. Antique automobile parts are rare and difficult to find, so we choose silicone DOT 5.
    Best Regards,
    John
     
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