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Discussion Starter #1
OK, first off I'm not here to go into a debate about Dot 5 verses Dot 3/4 brake fluids, I've already been through all the debates on several different forums...

My question... is there a superior Dot 5 brake fluid brand or is all Dot 5 pretty much the same? I will always use the best quality if one exists.

Thanks so much in advance,

Jason
 

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5.1 is the best . ;). Just kidding.


I don't know who makes the brand that H-D sells with their name on it, but it's pretty good. Otherwise I'd just go with Wagner.

Be sure to avoid undue motion of the bottle, and pour it slowly. It takes forever to get all the bubbles out once it gets aerated. ( not kidding )

Z
 

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castrol srf for top of the line and motul 660 for a cheaper alternative. It's what the serious guys that i track with use.
 

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not sure where exactly you are, but i get mine from wine country motorsports here in denver. They have a location out your direction by sonoma raceway.
 

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Discussion Starter #6
Thanks for there recommendation Z-Ray and carboy78, that helps...

stephen_wilson, don't mind spending pennies more for quality with something I'll be changing every 2 years, it's not that much more money and I'd rather only cry once then find out something down the road by going with a cheaper product.

Thanks,

Jason
 

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Discussion Starter #7
5.1 is the best . ;). Just kidding.

Be sure to avoid undue motion of the bottle, and pour it slowly. It takes forever to get all the bubbles out once it gets aerated. ( not kidding )

Z
Seriously, I know that one, that fluid will be sitting for a month not moving before it gets pour, and poured very carefully ;)

Jason
 

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Discussion Starter #10
For the sake of being specific, DOT 5.1 is not a silicone brake fluid and it can not be mixed with 5.0.
Yep, I'm aware of that, they really screwed up with naming that one, they should have called it 4.1 or 6, haha...
 

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For the sake of being specific, DOT 5.1 is not a silicone brake fluid and it can not be mixed with 5.0.
I know the OP knows the difference, and hence my ;) .

But it certainly doesn't hurt to point that out in any case. The Naming of DOT 5.1 has got to be in the top 10 of DOT goofs....... aside from Nixons 55 mph mandate.

Z
 

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Big difference is dot 5 is the only over 70 percent silicone based. Does not absorb water unlike 3,4 and 5.1. I would assume all dot 5 should be very similar. I assume you are using it because of this quality. Note I have heard some people say brakes feel a little more spongy because silicone is more compressible, don't know how true this is.
 

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Thanks for there recommendation Z-Ray and carboy78, that helps...

stephen_wilson, don't mind spending pennies more for quality with something I'll be changing every 2 years, it's not that much more money and I'd rather only cry once then find out something down the road by going with a cheaper product.

Thanks,

Jason
jason, using dot 4 brake fluid in a street car, especially if you tend to use the brakes hard, such as driving mountain roads, or winding country roads, thats fine. it mixes with dot 3 just fine. but i agree that spending the extra money to use dot 5.1, even though it also mixes with dot 3/4 fluids, is a waste of money, especially if you are changing the fluid out every two years. do yourself a favor and run dot 4 fluid and leave the dot 5.1 to the racers.
 

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".........Note I have heard some people say brakes feel a little more spongy because silicone is more compressible, don't know how true this is.
c'mon physics majors, let's hear the truth. Isn't there some important "law" of physics that postulates liquids are not compressible ???

It's my understanding that the issues with a soft pedal are primarily due to microscopic air bubbles. Can one get rid of all of them ??? I don't know...


Z
 

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c'mon physics majors, let's hear the truth. Isn't there some important "law" of physics that postulates liquids are not compressible ???

It's my understanding that the issues with a soft pedal are primarily due to microscopic air bubbles. Can one get rid of all of them ??? I don't know...


Z
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Lol, all fluids are compressible to a point. Compressibility includes the microscopic air bubbles as this is needed to rate the liquid. Cannot rate a brake fluid on theoretical performance or someone may die. I am sure that if your spend the time to avoid introducing them and bleed out a lot of fluid, you can have good results. But when you google it, you will see a lot of reports spongy pedal. I think that if I was racing I probably would use 5.1 to get the increased temp range and not worry about H2O absorption. For me a spongy pedal would drive me crazy.
 

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There is a reason Dot5 is not recommended for use in ABS systems .... compressibility due to
it's ability to trap air .
 

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Discussion Starter #20
So I've heard from other that have switched over recently to the Dot 5 from Dot 3 that they barely notice a difference, a slightly softer pedal like your rear drums aren't tightened down enough, but barely, some say they didn't notice any difference. Others have reported that they had a "soft squishy pedal" and then redid the bleeding process and the squishiness went away, poor brake bleeding, maybe these people did what you said Z-Ray and shook the bottle or got air bubbles when pouring into the master cylinder...

Anyway, not to concerned, with as much as I drive the car I probably won't remember what it felt like previously ;) it's what I'm doing anyway for multiple other reasons.

J
 
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