This should be done every 2 years or 24, 000-30,000 miles. To top off brake fluid, you'll need to locate your brake fluid reservoir. Since brake fluid eats away at the paint on cars, it's often recommended that you never poor directly from the container into the reservoir. Pop off the medal clamp on the reservoir by prying it loose with a screw driver. Replace lid and clamp.
Brake fluids tend to absorb water.
Never top off fluids during wet or humid conditions. To top off fluids, open the hood of your car and locate the fluid reservoir. You can pour the fluid directly into the reservoir. Store contents in airtight container and never use in temperatures under 32-degrees farenheit. Low or non-existent cooling levels can lead to expensive repairs and permanent engine damage.