If you feel that the shirt is ruined and you have nothing to loose, I would try Cascade dishwasher detergent. I have found that this stuff works wonders on stains, but becare it will bleach the spot if left on very long. I usually put a blob of Cascade and then take a toothbrush and softly brush it in, flip the shirt inside out and do the other side as well. Wash according to the fabric type (I use warm on most things). Good luck.
pat