How to Check Brake Fluid Level: 2025 GMC Sierra 3500 HD AT4 6.6L V8

Checking the brake fluid in your 2025 GMC Sierra 3500 HD is easy and should be done once a month. On some GMCs, the owners manual suggests pumping the brake pedal 25 times before looking at the fluid level, be sure to check your owners manual to see if this applies to your 2025 Sierra 3500 HD. In addition to checking the brake fluid level, you want to look at the color of the brake fluid in your Sierra 3500 HD - if it is dark in color or it has been more than 2 years since you have changed it, you should consider having it changed - this will help make the internal components (which are expensive) last much longer.If you need to add fluid to your Sierra 3500 HD, it is important to check your owners manual for the correct type to add - it likely be either DOT 3, DOT 4 or DOT 5, also known as silicone brake fluid. Be sure to discard bottles of brake fluid that are over a year old - brake fluid sucks the moisture out of the air and the water vapor in the fluid can quickly rust out the brake lines in your Sierra 3500 HD.