There's no single answer, as driving habits and climate play a role. However, a general scientific recommendation is to change your brake fluid every 2 years or 40,000 kilometers, whichever comes first.
Brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. This water contamination lowers the fluid's boiling point, leading to a spongy brake pedal and reduced braking efficiency, especially under heavy use.
While some modern cars may have longer suggested intervals, testing the fluid's moisture content with a tester is the most scientific method. For optimal safety and performance, adhering to the 2-year rule or your vehicle's manufacturer-specific schedule is a reliable and scientifically-backed practice. Don't wait for symptoms; make it a part of your regular maintenance.
