PB Blaster is a much better penetrating oil than WD-40. WD-40 was in fact never meant to be a penetrating oil--it's a Water Displacement (hence the name) oil, originally formulated to keep the Atlas missile from rusting in the silo. It works, kinda-sorta, in the penetrating oil role, but is decidedly suboptimal.
https://en.wikipedia.org/wiki/WD-40
https://en.wikipedia.org/wiki/WD-40