Dot 5 Brake Fluid?

#1
Just throwing this up for discussion..Is dot 5 fluid really worth installing?. I have heard that it is a good idea to use this in a car that is not driven that often. It has the ability to resist moisture build up. Also there is 5.1 fluid. What do you think?
 

wristpin

Well Known Member
#2
Ive swapped out dot 5 for dot 3 and 4 for years on motorcycles and never had a problem. Using a brake bleeder to suck all the old fluid out is best way so it doesnt keep mixing as you try to bleed pedal method. Dot 5 has never created seal or hose destruction issues on any bikes. Some swaps go back 30 years.
 

IMBVSUR?

Well Known Member
Supporting Member 2
#3
The differences are glycol based versus silicone, boiling points, compressibility, and if they are hydroscopic ( absorb water ) I have always thought that Dot 5 was originally invented towards things like the military where they knew moisture was an issue. Then there is performance, and some say that Dot 3 and 4 are better performing due to resisting heat better. I have seen one bike that the rear brake line was routed too close to the exhaust and the fluid failed ( my neighbors wife's bike when we were riding ) Changed the fluid and moved the line slightly and no problem. However, like Wristpin said, I have not seen any corrosion or hose destruction. That's the good part of Dot 5, and your paint.
 

1958 delivery

Well Known Member
Supporting Member 2
#8
DOT 5.1 is not silicone based as 5.0 is. 5.1 is same as 4 just has higher boiling temp
DOT 5 is silicone based and has higher boiling temp then DOT 4
DOT 5.1 HAS highest boiling temp of all
 

409gang

Well Known Member
#10
I put DOT 5 in my Corvette back in 1990 and have not touched the brakes since. Before that every time I wanted to drive it I had to work on the brakes as one or more of the calipers was leaking. Corvettes have 4 piston calipers at all 4 corners and they are a real pain in the A$$ to fix. I got SS sleeved calipers rebuilt the master cylinder flushed out all the brake lines and put in the DOT 5. The brake pedal is a little spongy compared to the DOT 3 due to the compression properties of the DOT 5 (my car has manual brakes) but its worth it as I am not road racing my car and I never worked on the brakes since.
 
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