PB Blaster works. It can take three days to a week before it does anything, but it does work where most "penetrating oil" products are completely worthless.
I'll stick with the Kroil. A big "Thank You!" to BITOG for letting me know this stuff exists. Where the PB needs a few days to a week, the Kroil needs ten minutes to two days. They both work and they both stink and they both show how most other penetrating oils aren't worth using even if you get them for free. Whichever one you use, the result can be amazing.