Most people will apply machine oil on the nuts and bolts in their cars or machines, so that the nuts and the bolts will not harden and rust, which can make it almost impossible to unscrew and remove the nuts and bolts. Even if you apply machine oil, however, the nuts and bolts can still rust especially if these have not been touched or re-oiled after many years. Here are some steps to help you loosen up nuts and bolts that have rusted into place.
Rust removers. The first and easiest step is to use rust removers. There are a lot of products out in the market today that are focused on softening the rust on nuts and bolts. If you think that the rusted area is only on the surface, then these rust removers are perfect for the job. They cannot really penetrate the space between the nuts and bolts, but if the rusted area is confined to the top, then it is possible for you to remove the nuts and bolts using the rust remover. These usually come in spray cans and all you need is to aim the nozzle at the particular nut or bolt that you want to remove. Read the packaging, and check to see how long you need to wait for the solution to take effect.
Heating the nuts and bolts. If the rust removers do not work, this probably means that the rust has penetrated the space between the nuts and the bolts. In this case, you should consider using heat as a way to loosen the nuts and bolts. You will need a small propane torch and gloves. Use the gloves to protect your hands from the fire and so that you can touch the nuts and bolts after they have been heated. Torch the area where the nuts and bolts are for a minute or two. The heat will make the nuts and bolts expand, as well as the holes where these are attached. This will make it easier for you to remove the nuts and bolts. Make sure, however, that you do not use too much heat and that you do not torch the nuts and bolts for too long. Otherwise, it can actually sold the iron pieces together.
Freezing. If heating does not work, you should apply some ice on top of the nuts and bolts for five minutes or so. Afterwards, use the torch again for a minute or two. The sudden temperature change can make the metal more malleable, and will allow you to easily remove the nuts and bolts.
Cutting. If the rust removers, heating, and cooling all does not work, your final course of action is to use a cutting device to simply cut of the head of the nut and bolt. Once the nut has been cut off, you should be able to easily remove the bolt.
Make sure that you always use caution when using the torch and that you keep the rust remover away from children who can play with the chemical and possible ingest it. With these steps, you should be able to loosen and remove old nuts and bolts that have rusted shut.