Automotive Service Excellence (ASE) Brakes Certification Practice Exam

Mixing different types of brake fluid should be avoided primarily because it can cause fluid contamination and chemical reactions. Different brake fluids, such as DOT 3, DOT 4, and DOT 5, have varying chemical compositions, including different bases (glycol ether or silicone) and additives. When mixed, these fluids can react chemically, leading to degradation of the fluid's properties.

This reaction may result in decreased fluid performance, such as reduced boiling points and compromised lubricating properties, which can ultimately impair the braking system's functionality. Additionally, the presence of contaminants formed from these chemical reactions can lead to corrosion within the brake system components, potentially causing leaks or complete failure of the braking system.

Therefore, maintaining the integrity of the brake fluid by using the specified type for the vehicle ensures optimal performance and safety in braking operations.