I realize it's rare to encounter a rusted bolt that will not budge,
but here's a trick in case you do:
Heat the area around the bolt with a propane torch, and touch a candle to the threads. The wax will be sucked into the opening around the threads, and the bolt can be removed easily. The heating and candle application may have to be repeated a couple times. This works on the same principle as "sweat-soldering" copper pipes, and will work where penetrating oil will not. (Always use care when and where you apply heat)
Try this on your next stuck bolt. You'll be amazed.
Heat the area around the bolt with a propane torch, and touch a candle to the threads. The wax will be sucked into the opening around the threads, and the bolt can be removed easily. The heating and candle application may have to be repeated a couple times. This works on the same principle as "sweat-soldering" copper pipes, and will work where penetrating oil will not. (Always use care when and where you apply heat)
Try this on your next stuck bolt. You'll be amazed.