By FMVSS116 standards, DOT 4 fluids must have a minimum dry boiling point of 446°F and a minimum wet boiling point of 311°F. DOT 4 is the grade applicable to most race engineered brake fluid in the world today, especially with regard to viscosity limit.
Besides, what kind of brake fluid to use?
The three main types of brake fluid now available are DOT3, DOT4 and DOT5. DOT3 and DOT4 are glycol-based fluids, and DOT5 is silicon-based. The main difference is that DOT3 and DOT4 absorb water, while DOT5 doesn't. One of the important characteristics of brake fluid is its boiling point.
Is synthetic brake fluid better?
All DOT3 & DOT4 fluid is syntheticie it is man made and does not have a petroleum base. DOT3 & 4 can safely be mixed. HOWEVER DOT5 (or 5.1) brake fluid is silicone based and must NEVER be mixed with DOT3 or 4.
Which is better DOT 3 or DOT 4 brake fluid?
Dot 3, 4, and 5.1 are glycol ether based. They are compatible, but like motor oils, you should use the recommended or higher grade fluid. Dot 4 and 5.1 also have borate ester to handle higher temperatures. DOT 3, 4, and 5.1 fluids are found in most brake and clutch systems.