Wire brush the bolt head bases, then repeated PB blaster soaks over time.
My upper ball joints are threaded and known to need ridiculous torque to unthread. I did the dental pic/wirebrush thing along the seam to clear it, then a PB blaster every few days a before the special socket arrived.
When I leaned back, pulling on the breaker bar, I wound up on my back. The threads were wet with Pb blaster when I then unthreaded it by hand.
Very surprised.