....Like You Mean It !!!
Look, you've gone beyond the stage when you can use Zen to get this sucker off. Now its time to show it that you mean business.
As has been suggested, wet it down with some cold penetrant oil first...that's its wake-up call. Then, rap that balky bolt on its head with a hammer a couple of times. Not hard enough to bend the oil pan but enough to get its attention. Then squeeze that fiesty fastener with your biggest baddest vise-grips. Set the vise-grips so you can hit the handle of the vise-grips with your trusty Harley wrench (hammer). Don't be afraid....get after it like you REALLY mean it. You should be able to scare it off once you set your mind to it.
When you are done, you will feel MUCH better.