Anyone go to DOT 4 fluid.

[NORCAL SS]

Going to do a pressure bleed on my truck with the wilwoods and prob going to put in some dot 4 wilwood or motul. Anyone done the swap?

 

[Khao5]

why did you decide to go with dot4 vs 3 ? higher boiling point ?

 

[NORCAL SS]

well got 3 bottles of motul dot 4 coming. I have the wilwood big brake kit on my truck so going to vacuum bleed it and see how the dot 4 works out. higher boiling point yes and i want to see if there is any pedal difference.

 

[Khao5]

dot 4 is less hygroscopic then 3 so maybe a slighter firmer pedal .

 

[NORCAL SS]

i will soon find out. Whats funny i bled my brakes with truck off and didnt feel that good but then had the truck runnind bled them and pedal got harder after bleeding them. I will do the same this time thats why I bought 3 bottles of the stuff.

 

[Khao5]

shop i used to work at did alot of limos and i noticed that too when i used to bleed the H2 stretches. which btw is a total P.I.T.A to do

 

[Physh1]

Yes, I went dot 4 a while ago. DOT4 is designed to absorb moisture slower than DOT3 and has a higher boiling point so, in theory, it may last longer between services/flushes.

I also noticed a better result when I bled my brakes with my truck running.

Cameron

 

[Smokymance]

I swapped to Dot 4 on my tbird back when i did the big brake upgrade...didnt really notice much...but why not!

 

[TowGMC]

DOT 3 is ooooold tech. DOT 4 specs have higher dry and wet boiling points. Otherwise they should both perform the same when both are fresh. The only way a DOT 4 would feel better than 3 is because the 3 in the car is old and has hygroscopically absorbed moisture. Brake fluid is NOT compressible, but water is, so old brake fluid in a car which has absorbed moisture over time will feel a slight bit spongy when compared to any new fluid. That's why all vehicle manufacurers specify a brake fluid change at 2 years.

But not all DOT 4 fluids are the same.
Valvoline off the shelf 3/4 from Autozone- dry bp is not even published on can, wet bp is just 311.
Castrol LMA- dry 509, wet 329
ATE 200 (OE Mercedes fluid)- dry 536, wet 396 (what I have on the shelf for my Denali)
Motul 600- dry 594, wet 421 (what I use in the race car)
Motul 660- dry 617, wet 399
Castrol SRF- dry 590, wet 518 the highest wet available but $70 per 33 oz bottle
ATE Superblue- same spec as ATE 200 but has been pulled off the US market because idiotic US laws say it's illegal to have a brake fluid that isn't amber in color.

 

[Ben]

I did dot 4 when I did my rotor and pad swap. Not much difference here but I know it'll last longer.