Kroil works really well. I had a can but finally ran out and now cannot find it locally.
Slanted_Mind said:1) Aircraft penetrating oil---do not recall the brand (roommate is an A&P mechanic)
2) PB Blaster
3) Liquid Wrench
All of the above make WD-40 look like water (WD-40 is not a penetrating lube BTW) Never tried Bust-it. May try it out.