How To Loosen Rusted Bolts with a Torch

Loosen Rusted Bolts

Use a Bernzomatic torch and a little elbow grease to loosen frozen, rusted or stubborn nuts and bolts.

  • For stubborn bolts, heat the bolt, then move the flame away and apply WD-40 against the heated bolt threads. The melting wax pulls itself into the threads to create a slippery surface.
  • Keep open flames away from fuel and brake lines, rubber fittings and other flammable parts and materials.


  1. Check thoroughly to ensure there are no flammable materials such as plastic or fabric in close proximity to the bolt you’ll be heating.
  2. Apply penetrating oil to the bolt and give it a few minutes to sink in. Use a rag to soak up and remove any residual oil.
  3. Turn on your torch and aim the flame directly at the bolt head. Move the flame in a circle around the bolt for 30 seconds.
  4. Use a socket wrench to rock the bolt back and forth until it loosens enough to be removed. The bolt is stubborn, repeat steps 2 and 3.


  • Read our General Safety Precautions before starting your project.
  • Read the instructions that come with your torch before beginning your project

What You'll Need


DuraCast™ 8000 Torch

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14.1 oz. MAP-Pro® Hand Torch Cylinder

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  • Keep a fire extinguisher or water source nearby in case of emergency.
  • Safety glasses
  • Work gloves
  • Wrench


  • Penetrating oil
  • Rag
  • Wax stick (optional)