The brake fluid flush is the most common and vital flush that must be conducted. Over time dirt, grime, dust, and water can get into the brakes, causing them to fail. To determine whether it’s time for a flush, take a look at the brake fluid. Healthy brake fluid should be clear, so it is time for a flush if it’s brown. If you smell burning, it could mean your brakes are failing, and you need to repair them immediately.