Vehicle manufacturers recommend brake fluid that meets or exceeds SAE (Society of Automotive Engineers) and DOT (Department of Transportation) specifications.

Brake fluid must have the following characteristics:

Low freezing point (not freeze during cold weather)

Water tolerance (absorb moisture that collects in the system)

Lubricate (reduce wear of pistons and cups)

Noncorrosive (not attack metal or rubber brake system components)

Maintain correct viscosity (free flowing at all temperatures)

High boiling point (remains liquid at the highest system operating temperature)

Standard brake fluid (DOT 3) is composed chiefly of equal parts of alcohol and castor oil. This combination of fluids works well under normal conditions but it easily boils and becomes a vapor under heavy-duty applications. Standard fluid also tends to separate when exposed to low temperatures.
The increasing requirements of brake fluid led to the development of silicone brake fluid.

After many years of research and development, a brake fluid that was acceptable under extreme operating conditions was developed. This fluid achieved low water pickup and good corrosion protection. The fluid also provides good lubrication qualities and rubber compatibility. Silicone brake fluid has been used in most military vehicles since the end of 1982.