Working under the vehicle often means dealing with rounded or damaged fasteners in critical areas like the chassis, suspension, drivetrain, exhaust, and aero panels (belly pans/covers).
Cleaning a rounded fastener before removal can make the job easier. Surface rust, dirt, oil, and other debris can worsen the damage and reduce tool grip. Use a degreaser or solvent to clear away contaminants before attempting removal. Once cleaned, a locking plier (Vise-Grip style) designed for rounded fasteners can provide a strong grip to break it loose. For added effectiveness, consider tapping the fastener lightly with a hammer to help break rust bonds or applying penetrating oil for extra lubrication. Taking these extra steps can save time and prevent further damage, making fastener extraction much more manageable.
CTA Tools recommends Parrot Pliers and Bolt Extractors.