Anyone have any good ideas for removing oil stains?

I spilt some cooking oil on my favourite old black tracksuit pants and I can't get it out. I tried putting some talcum powder on it, and I even tried putting them through the wash, but the oil stain is still there.
I'm wondering if I should try sending them to the dry cleaners, but seeing as these are old tracksuit pants I'd feel a bit stupid.

Oh, and I know they're old, but I'm not replacing them, that's out of the question.