I was raised working on old machinery, and have used everything from kerosene on up for getting rusted bolts out. I did not have access to a torch, but did have a VERY OLD AC welder, and over the years I got pretty good at burning the heads of bolts off with the welder and doing minimal damage to the surrounding material. The old time Liquid Wrench was and still is good where you have a lot of bolts to loosen, but it does take time. I have over the years used about everything on the market, and for years believed that Kroil was about the best there was, and I still have a half gallon of it that I keep in a spray bottle for large applications.
A few months ago I bought a can of Sea Foam Deep Creep to try. After using it a few times on applications where I did not expect it to help I have bought a couple more cans to keep on the shelf in case i run out. I can safely say that in my non controlled tests it is by far the best thing I have seen for loosening rusted and stuck parts and bolts. The first time it really got my attention was when I was working on a neighbors Yerf Dog CUV, where the bearings that carry the brake assembly on the axle were rusted in place in the brake housing. I had tried removing them with some serious use of a punch and hammer, but not been able to budge them. In desperation I grabbed the Deep Creep and gave them a quick shot. When I came back a couple minutes later it only took a few taps to remove each of them. I have been a believer ever since.
"The Constitution is not an instrument for the government
to restrain the people, it is an instrument for the people to restrain the
government lest it come to dominate our lives and interests." Patrick Henry