Brake Fluid Compatibility
Brake fluid types, boiling points, and compatibility. Glycol-based fluids (DOT 3 / 4 / 5.1) are hygroscopic and mutually compatible; DOT 5 silicone must never be mixed with them.
| Type | Chemistry | Dry Boil | Wet Boil | Paint | Mixes With |
|---|---|---|---|---|---|
| DOT 3 | Glycol ether | 401°F (205°C) | 284°F (140°C) | Strips paint | DOT 4, DOT 5.1 |
| DOT 4 | Glycol ether + borate | 446°F (230°C) | 311°F (155°C) | Strips paint | DOT 3, DOT 5.1 |
| DOT 4 LV / Super DOT 4 | Glycol + borate | 500°F+ (260°C+) | 356°F (180°C) | Strips paint | DOT 3, DOT 4, DOT 5.1 |
| DOT 5 | Silicone | 500°F (260°C) | 356°F (180°C) | Paint-safe | ONLY DOT 5 — segregated |