The minimum wet boiling point determines whether a brake fluid is DOT 3 or DOT 4. For example:
DOT 3 = 284F
DOT 4 = 311F.
Synthetics can be DOT 3, DOT 4, or DOT 5.1 while all silicon brake fluid is DOT 5.
Mine was an 80 Camaro that was basically a race car on the street. The ABS system moves brake fluid at a rate the silicon can't match plus the orifices that it has to pass thru it's to viscous IIRC from reading.