4.8IS Oil Filter Cap Jammed?

[cannan]

I changed my oil this weekend but I couldn't get the oil filter cap off. It's in such a tight space right there by the oil pan that maybe I'm just not able to get enough leverage to get the thing off. I'm certain that I'm turning in the right direction as I imagine that its the same as on my 330 which I've done a bunch of times with no fanfare.

Anyone with a 4.8IS have any ideas or tricks that might help? My local indy did my first two oil changes on the truck and I could just swing by there but I'm hoping to get this figured out myself for future reference.