Upper control arm removal.

My preference for rust busting is KROIL. Soak for a hour has done the trick 90% of the time.

If that fails I use a Dremel tool with a cut off wheel. (Recommend use of eye protection and a mask unless you like dirt in your eyes and sucking it down when you breathe.) If I do a decent job of cutting a side off the nut, a socket wrench will break it loose. If not, I pull out my BFH and a cold chisel. Never failed to get the nut to rotate.