Which factor can contribute to poor brake performance?

Old or contaminated brake fluid can significantly contribute to poor brake performance for several reasons. Brake fluid is crucial for the hydraulic system that operates the brakes. Over time, brake fluid can absorb moisture from the air, leading to a condition known as hydraulic fluid contamination. This contamination reduces the boiling point of the fluid, which can result in vapor lock under high-temperature conditions. Vapor lock occurs when gas bubbles form in the fluid, causing a loss of hydraulic pressure, and ultimately making it difficult to engage the brakes effectively.

Additionally, contaminated brake fluid can lead to corrosive effects on brake components, such as the master cylinder and brake calipers, which can further degrade braking performance. Old brake fluid may also have a decrease in viscosity, making it less effective in transmitting the force from the brake pedal to the brake components.

In contrast, the other factors mentioned, like functioning brake lights, high-quality brake pads, and accurate wheel alignment, contribute to safe and efficient vehicle operation but do not directly impact the hydraulic performance of the braking system in the same critical way as the condition of the brake fluid does.