I have heard of people using many things to unstick engines. Diesel, ATF, Marvel Mystery Oil, PB Blaster, Kroil, ect. WD40 is probably the worst penetrant on the market. Try PB Blaster or Kroil and be patient and let it do its magic.

Also, do a search here on the 'bolt. This subject has been covered many times.

Never hold your farts in. They travel up your spine and into your brain...that is where crappy ideas come from.