"Hydraulic fluid" is typically the name used for brake fluid > as the brakes use a hydraulic piston/cylinder design.

MB use DOT-4 fluid. [at least my 97 C230 uses DOT-4]

Brake fluid should be changed every two years > as it is "hydroscopic" >> it absorbs water vapor > which in turn lowers the boiling point of the fluid > which lowers the thermal efficiency of the fluid.

There is a specific "power steering fluid" for the power steering system of the car