Auto manufacturer recommend brake fluid that meets or exceeds SAE (Society of Automobile Engineer) and DOT (Department of Transportation) specifications, only brake fluid that satisfies then requirements should be used.
Brake fluid must have the following characteristics:
1. Maintain correct viscosity (free flowing at all temperatures);
2. High boiling point (remain liquid at highest system operating temperature);
3. Non corrosive (not attack metal or rubber brake system parts;
4. Water tolerance (absorbed moisture that collects in system:
5. Lubricate (reduce wear of piston used cups); and
6. Low freezing point (not freeze in cold weather).