I have used both Kroil and PB Blaster. I think Kroil works a tad better for really nasty frozen "items". I use more PB though because I have a lot of it....(logic)
WD-40 isn't even on the same planet as those two products. I used WD-40 for cleaning ocaisionally but that's about it.
Hands down Kroil outshoots PB Blaster. I have a twin pack of Silikroil, claimed to have silicon lube properties on top of the regular Kroil....let's see how it performs in my frozen shift bolts