Difference in brake fluids?

Joined
Feb 28, 2015
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MD
In preparation for a brake job soon, stupid question.

Is there a better brake fluid than another? I worked in a dealer forever where we either used BG fluid or Berkebile fluid for brake fluids. I assumed the Berkebile was as cheap as they could source, but it’s a company that has tons of shop supplies so I don’t know if it’s bad or not.

I have some dot 3 Berkebile I could use when doing my brake job on my Mazda (to replace all the fluid / “flush” it for lack of a better word). But would locally available Peak O.E. Asian DOT 3/4 fluid be better? Is there really a difference?

Car calls for DOT 3 on the cap.

Thanks!
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As far as numbers goes, 4 and 5.1 have a higher boiling point than 3 but a lot of people claim that 3 tends to absorb less moisture than 4 and 5.1. For a daily car I wouldn't think to much about which manufacture it comes from as the differences between them are pretty minute unless you're looking for specifics/absolute best (like Castrol SRF vs Motul 600.)
 
For DOT 3 there are some brands that are slightly yellowish vs clear but I don’t know what difference that makes. The Napa brand DOT 3 they sell up here is clear. I changed out a master brake cylinder and bled the lines so the fluid in the reservoir looks clear, making it look like new. Just another obsessive compulsive thing for those interested. :D
 
I swear, the Prestone that I used seemed to go green quickly, but I blamed it on going into an old car. The Supertech that I've been using since seems to do the same thing? Just darkens quickly. Maybe name brand / better brand controls color better, not sure. I haven't seen enough info to make me change though.
 
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I have been been using this stuff lately.
“100k fluid life.” 🤷🏻‍♂️

I am not a huge believer in moisture contamination being an issue with modern brake systems and DOT3. Perhaps this stuff can last 100k since it has superior corrosion inhibitors?
 
As far as numbers goes, 4 and 5.1 have a higher boiling point than 3 but a lot of people claim that 3 tends to absorb less moisture than 4 and 5.1. For a daily car I wouldn't think to much about which manufacture it comes from as the differences between them are pretty minute unless you're looking for specifics/absolute best (like Castrol SRF vs Motul 600.)

Yet online I found the opposite from manufacturers, DOT4 attracts less moisture than DOT3.

There's a case to be made for low viscosity fluids, they allow for a more responsive brake system (both when applying and when releasing the brake) and this benefit is even greater when you have a fast cycling ABS/ESP (think 25 cycles per second here).

Some fluids swell seals more than others. Some seal swell is good, but you can have too much of a good thing.
 
Yet online I found the opposite from manufacturers, DOT4 attracts less moisture than DOT3.
It is tough to figure out the semantics. The very old Stop Tech article stated that DOT4 was less prone to moisture absorption, but when it did absorb some, the boiling point drops exponentially more than DOT 3. In "some" cases it could end up less than DOT 3.

I live in the flat lands of the great lakes area and always drive a non-descript daily driver vehicle. I tend to follow the idea already stated that moisture degradation is generally a moot point with occasional changes and I have always used the DOT 3 all of my vehicles recommend.
 
With appropriate fluid in appropriate equipment I think it's a moot point aswell. I do know of a few cars (models) turning the OEM fluid green in short order, probably not a good sign. But other models can go a decade and the OEM fluid still looks fresh.

My car recommends DOT 4 LV, so that's what I use
 
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