Here are your stuck bolt removal options...
1) Penetrating Oil - Yes. This will work very well. Just make sure you soak it all day or overnight. The best IMO penetrating oil I've seen is Kano Labs Kroil oil. http://www.kanolabs.com/.

The best advice I could give is being patient. Take your time and think about it. Sometimes going to a bigger tool is not the answer. You will just risk breaking the bolt. When you do get the nut or bolt to move, step back and take a break for a second. Then cover it with WD-40 or equivalent. Then turn the nut or bolt the other direction (tightening it), and then loosen it. You'll be rocking it back and forth slowly, loosening the bolt. Meanwhile spraying it with WD-40.


2) Use Heat its your best bet Most of the time it will work for you. Start with small amounts of heat and gradually increase it. Remember if you tried lubricant clean it all of as it is flammable. As far as where to put the heat, remember heat expands, so you would heat a nut. For bolts threading into something you heat the area around it.

BE CAREFUL NOT TO MELT ANY OF THE BOOTS, REMEMBER TO LOOK BEHIND WHAT YOUR TORCHING.