When checking brake fluid, what is an important characteristic to note for DOT 5 fluid?

When checking brake fluid, an important characteristic of DOT 5 fluid is that it is silicone-based. This is significant because silicone-based fluids are non-hygroscopic, meaning they do not absorb moisture like glycol-based fluids such as DOT 3 and DOT 4. This characteristic helps prevent internal brake system corrosion, which is a common concern when using fluids that can absorb moisture.

The silicone-based nature of DOT 5 fluid allows for better performance in certain applications, particularly in high temperatures, and it maintains its properties even in the presence of water. This further emphasizes the importance of using the correct type of brake fluid in a given system, especially since DOT 5 cannot be mixed with glycol-based fluids (such as DOT 3 and DOT 4) without risking contamination and performance issues.

Understanding that DOT 5 is silicone-based helps technicians make informed decisions about brake fluid compatibility, maintenance, and safety.