Rust is the nemesis of many do-it-yourselfers and mechanics. Not only does it look terrible, it can make such things as metal screws seemingly impossible to remove. If you are faced with loosening rusted screws, don't give up hope. While your job will be more difficult than normal, it's not a lost cause. All that's required are a few basic tools that can be found at any hardware store, some time and a bit of extra elbow grease.
Spray or pour some penetrating oil onto the head of the screw. If you have access to the threads of the screw, you should coat them in penetrating oil as well.
Allow the penetrating oil to soak on the screw for five to ten minutes. If you're not in a rush, you can even let the oil soak into the corroded screw overnight.
Fit the screwdriver into the head of the screw. Be sure to use a screwdriver that tightly fits the head of the screw. If it's too small, you may strip the head of the screw, making your job much more difficult.
Hold the screwdriver steady and tap the handle with a hammer, driving the screwdriver into the head of the screw. This will ensure the screwdriver is fitted tightly.
Turn the screwdriver clockwise, as if you wanted to tighten the screw. This will help break the screw loose. Then, using one hand to turn the screwdriver and the other hand to push down on the top of the handle, turn the screwdriver counter-clockwise in order to loosen and remove the screw.
Heat the screw with a small propane torch. If you don't have access to a torch, you can use a soldering iron or even a hot glue gun. Heating the metal of the screw causes it to expand and contract, thus loosening it. If using a torch, be careful not to burn off or melt the head of the screw.
Fit the screwdriver into the head of the screw while the screw is still hot. Then tap the handle of the screwdriver with a hammer, ensuring the screwdriver is tightly fitted into the head of the screw.
Twist the screwdriver clockwise to break it loose and turn it counter-clockwise in order to loosen and remove the screw. Again, use one hand to turn the screwdriver and the hand to apply downforce on the handle.
If the screw is not turned in completely, allowing the head to remain above the surface, you can use locking pliers to grip the head of the screw and turn it out. This is effective especially if the head of the screwdriver is so rusted that your screwdriver does not fit securely. Also, if the head of the screw is rusted out, consider purchasing an impact driver. These tools can come with various attachments, including screwdriver bits. You simply place the driver against the rusted screw and hit it with a hammer. This drives the bit into the head of the screw, which creates a tight fit so that you can remove the screw.
Wear safety glasses. Be careful using a torch around penetrating oil. It can be flammable.