Why does the brake fluid need changed at 30,000 mile intervals?

Hello, While brake fluid has a high boiling point, it can still boil. Also, no system is perfect, so contamination can still get into the brake system though it is sealed. The service interval for flushing and bleeding the brakes is established through years of testing, and helps prevent premature failure of brake system components. Also, dirty fluid can cause the ABS module to function improperly, and replacing the ABS module is not typically considered economical. Check your owners manual for required service intervals, and follow those. You will likely prevent a failure at some point in the life of the vehicle.