Rusted caliper bolts will make it nearly impossible to replace your brake pads. The caliper bolts hold the caliper in place. The caliper is what houses the brake pads and makes it possible for you to slow down. When i'ts time to replace the brake pads, you need to be able to take the caliper bolts off (or, on some vehicles, at least loosen them). If your caliper bolts are rusted, however, you'll need to purchase new caliper bolts from your vehicle's dealership and use a bolt-out kit to remove the old bolts.
Spray the rusted bolts liberally with penetrating oil and allow the bolt to sit in oil for 10 minutes.
Spray the bolt again and fit one of the bolt-out sockets over the rusted bolt. The socket should fit very snugly over the bolt. If necessary, use a rubber mallet to tap the socket over the end of the bolt head.
Remove the rusted bolt by turning it counterclockwise with a socket wrench. This will effectively destroy the bolt because the socket will have teeth that grab onto the rusted bolt and force it out of position. It will, however, remove the bolt.