Apply penetrating oil and let it soak
Tap the bolt head lightly to help the oil work in
Use the correct-size wrench or socket
Turn slowly with steady pressure
Try tightening slightly first, then loosening
Use heat on the surrounding metal if safe
Cool the bolt after heating to help break the rust bond
Use a wire brush to clean exposed threads
Strike the bolt head with an impact tool or hammer
Use an impact wrench or manual impact driver
Apply more penetrating oil and repeat the process
Use locking pliers if the head is damaged and accessible
Cut a new slot or use a bolt extractor if needed
Drill out the bolt if it cannot be removed
Replace the bolt after removal