Which Brake Fluid For Road and Track?

[eastla]

I think Ill stick with the Dot 4.

I have a feeling that it may be safer than the Dot 5.1

From what I was told by the service department at Mazda; Dot 3 or 4 is recommended but not 5.1.

I dont want to damage anything.

[Matty]

Motul Dot 5.1 is recommended for cars with ABS and is superior to any of the standard dot 3 or 4 fluids.

Motul RBF600 is a high performance DOT4 brake fluid and has a higher dry and wet boiling point than the 5.1. I've read that it goes off sooner than the 5.1 which is untrue as shown by the wet boiling point (or boiling point for 1 year old fluid or fluid with a bit of absorbed water)


Motul Dot 5.1
Dry boiling point 270 °C
Wet boiling point 185 °C

Motul RBF600
Dry boiling point 312 °C
Wet boiling point 216 °C

Has anyone manage to get brake fade with the 5.1 on the track?.

The wet boiling point is rated at a certain percentage of water absorbed, not "after 1 year". The rate of absorption is not the same for different fluids.

[drifter]

I think Ill stick with the Dot 4.

I have a feeling that it may be safer than the Dot 5.1

From what I was told by the service department at Mazda; Dot 3 or 4 is recommended but not 5.1.

I dont want to damage anything.

Dot 3 + 4 + 5.1 are interchangeable. The cap on my NB8B brake fluid reservoir says ONLY to use dot 3 but I have used dot 5.1 for the last 40,000km's without a problem. It was what MX5mania put in my car when I first had it serviced.

It’s dot 5 silicon fluid that you should avoid.

The wet boiling point is rated at a certain percentage of water absorbed, not "after 1 year". The rate of absorption is not the same for different fluids.

Yeah I know. I believe its 3% water for wet boiling point measurements. I was just using 1 year as a rough rule of thumb (that I read somewhere). 3% doesn't mean anything to us because we can't measure it.

You should change the brake fluid every 12-24 months regardless of how little the car is dríven. Sooner if you track the car or rack up a lot of km's.
Brand new sealed brake fluid has a shelf life of 2 years so don’t buy a bottle with a thick layer of dust on it

[manga_blue]

FWIW I've boiled fresh DOT 4 at Barbagallo. I have not been able to boil DOT5.1 anywhere yet. That's with a pretty stock motor, so I'm not getting the extreme speeds that some of the turbos and serious n/as get.