What should be checked in a brake fluid system for a successful inspection?

In a brake fluid system, the key aspect to be checked for a successful inspection is that the fluid maintains height upon pedal pressure. This is crucial because it indicates that the brake system is functioning properly and that there is sufficient fluid available to engage the brakes effectively. If the fluid level drops significantly when the brake pedal is pressed, it could indicate a leak in the system or other issues that could compromise braking performance.

Other aspects, such as the cleanliness or odor of the fluid and matching the fluid to the vehicle brand, can be important but are secondary to ensuring that the hydraulic system operates effectively under pressure. The fluid's color may also provide some information about its condition, but the critical factor for safety is the ability of the fluid to maintain pressure and provide effective braking. Therefore, the ability of the fluid to maintain height when the pedal is engaged is the best indicator of a healthy brake fluid system.