3500GT brake Fluid DOT5 or "Oltimer" | FerrariChat

3500GT brake Fluid DOT5 or "Oltimer"

Discussion in 'Maserati' started by TridenteFury, Oct 22, 2014.

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  1. TridenteFury

    TridenteFury Karting

    Sep 28, 2014
    78
    Ciao Tutti,

    What would you recommend for a great brake fluid for 3500GT ??
    Am using DOT4, but noticed that within less than a year it wasn't good anymore, too much water in it... I've heard that DOT5 would not attract any water, and thus can last a very long time, without even the risk of rust... Can this be used without any problems in 3500GT brake systems?

    I also heard about an "Oldtimer" brake fluid, which should protect oltimers at best... Anyone heard of it??

    Molto Grazie
    Carlito
     
  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Brian Crall
    DOT5 does not absorb water but it is well established that brake systems do get water in them and by federal government tests it is about 3% dilution in a year on a car seeing average use. DOT 4 keeps that water in solution, evenly distributed throughout the brake system. DOT5 allows the water, which is heavier, to settle to the bottom and concentrate, rusting the brake parts local to the water. In independent testing it has not shown any ability to prevent rust in brake components and in some cases makes it worse.

    Additionally the low part of the brake system is also where the heat is generated. Now we have brake fluid with a boiling point of 212 degrees concentrated at the point of highest heat instead of our 500 or 600 degree boiling point fluid.

    DOT5 brake fluid has a vastly higher degree of compressibility and gets worse as temps increase. This factor alone was sufficient to prevent its authorization for use by the TUV, the German equivalent of the DOT.


    The only known advantage to DOT5 is that it will not damage paint. Id suggest not pouring brake fluid of any type on the paint of your car.
     
  3. staatsof

    staatsof Nine Time F1 World Champ
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    Mar 13, 2005
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    +1.

    I've used DOT 5 long term on once car and the biggest problem it has is the accumulation of water at the caliper seals. That's kind of hard to bleed out too. If you do begin to use the brakes heavily they will boil that water very quickly. It has a softer pedal as well. It's has not so easy converting back. It does seem to make the masters last longer in my view but you do need to bleed the caliper cylinders just as often. Mixed bag.

    LHM is much better than both but then you can use that.
     
  4. TridenteFury

    TridenteFury Karting

    Sep 28, 2014
    78
    Thanks for the excellent insights...

    So DOT4 would be better as long as I monitor water content regularly and if too much, flush out and replace the fluids with fresh DOT4?

    Cheers
    Carlito
     
  5. Rifledriver

    Rifledriver Three Time F1 World Champ

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    That is my opinion. Not sure what oldtimer fluid is but if it is designed to absorb water more slowly that would be a plus.
     
  6. staatsof

    staatsof Nine Time F1 World Champ
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    correction!
     
  7. 3500GTista

    3500GTista Rookie

    Dec 19, 2013
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    Maryland
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    Alan Michaels
    Carlito,
    I've suffered with this question and poor results with conventional fluids for two decades with premature rust formation, primarily, on the disc brake pistons. Just recently as I, again, overhaul my brakes, Kerry at MIE (Maserati Club, Maserati Parts, MIE Corp. MaseratiNet Store) recommended the Castrol GT LMA synthetic fluid as the Girling-recommended fluid. I've purchased this on Amazon and will not know the results for a few years.

    Buona fortuna,

    Alan
     
  8. alberto

    alberto Formula 3

    Aug 25, 2001
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    Alberto
    If you aren't changing the brake fluid "for a few years", then it's not a surprise you are having issues with rust in your brake pistons. It should be changed every year, every two years tops. Dot 4 naturally absorbs water, which causes the rust and spongy pedal. Even if you use a high quality brake fluid like LMA, it will absorb water because the system is not air tight and it will draw water from the humidity in the air.

    I just rebuilt the calipers on a car that was fully restored in 2006 by a highly rated shop, so I'm sure they used good quality fluid. Car's been driven all of 300 miles since; brakes locked up on the test drive. Brake pistons were literally full of water.
     
  9. Volante 43

    Volante 43 Karting

    Nov 8, 2011
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    Rudolf J Visser
    #9 Volante 43, Oct 23, 2014
    Last edited by a moderator: Sep 7, 2017
    This is nonsense !
    I'm using Dot 5 Silicone Brake Fluid for almost 12 years now in al my classic sportscars, Aston's, Maserati's, 911's, Morgan.............................
    Never had any problem with this product Automec - Silicone DOT 5 Brake & Clutch Fluid 1 Litre
    Image Unavailable, Please Login
     
  10. staatsof

    staatsof Nine Time F1 World Champ
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    Not it's nonsense at all but if you flush the fluid regularly just like conventional brake fluid then the issues are greatly mitigated. The trouble is people hear about the fact that it does not absorb water (actually a weakness in some ways) and think "Hey I don't have to flush the fluid regularly" and that IMHO is where the big error is made. Not good for ABS systems. It takes a long time for bubbles to come out of solution as well. I'm still using it on one car but I've greatly modified how I'm using in that car. Regular and frequent flushing solves most of these issues in braking systems but people don't ...
     
  11. DWR46

    DWR46 Formula 3
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    #11 DWR46, Oct 23, 2014
    Last edited: Oct 23, 2014
    I agree with Volante 43. I have used Dot 5 fluid since 1977 in over 100 cars. Never had a problem. All the cars have had good firm brake pedals after being bled correctly. I change the fluid every 10 years, but it never needs it, I just feel guilty leaving it in the car. True, the Dot 5 fluids will not release bubbles quickly, so I do not shake the bottle before I install it. We do not use it in our vintage race cars, as is does have a "window" of compressibility. Also, it is not usable in cars with ABS brakes, as it will not flow through the microvalves in the controller. However, for street use in collector cars, it is perfect.

    To be clear, I am speaking about Dot 5 Silicone Fluid.
     
  12. jasu

    jasu Rookie

    Oct 17, 2011
    25
    Finland
    DOT 5 or DOT 5.1?

    DOT 5.1 is "compatible" with DOT3 and DOT4, but not with DOT5!!!
    DOT 5 is silicone -based, others are glycol -based.

    Without perfect flushing, there will be problems when mixed DOT 5 to others, in some case even flushing isn't enough, and gaskets must be changed also.
     
  13. staatsof

    staatsof Nine Time F1 World Champ
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    Well I found out the hard way at the track when my brakes boiled way too soon. Flushing didn't fix it either. When I took the calipers apart they all had water at the ends near the seals. That was evidence enough for me. As I said, I'm still using it in that car but I bleed it much more regularly now especially if you're using it.

    If it mostly sits then the brakes won't get warm and perhaps that reduces the water sneaking by the seals?

    But I've seen it happen first hand.
     
  14. BJJ

    BJJ Formula 3
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    Feb 25, 2014
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    Rifledriver summarized the findings of German TÜV perfectly.

    It is an advantage that DOT 4 and 5.1 absorbs water and not a disadvantage if a car is in regular use, exactly for the reason he said.

    DOT 5 is fine for cars that are not used or very rarely used. And if so only in sunshine and moderately. The military uses DOT5 for vehicles in the depot. For switching to DOT 5 it is strongly recommended to replace all rubber parts in the brake system at the same time, since the conventional DOT 4 or 5.1 becomes absorbed to some extent by rubber and is released therefrom again. A simple flush does not warrant having removed all conventional fluid from the brake system.
     
  15. Rifledriver

    Rifledriver Three Time F1 World Champ

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    It is my understanding that the military is going away from silicon fluids due to some long term problems. I have not been able to find out what specific problems they are encountering but get the feeling it has been an issue for some time. Due to the nature of their usage I suspect it is the water pooling issue.
    Water is going to get in, that we know, it becomes a matter of where you want it once it is there.
     

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