Make sure you are turning the oil drain plug instead of one of the engine mounting bolts.

Lime,

Ur smart to post here before stripping the head on that drain plug....

First, comply with the suggestions of the previous posters.

If still no joy, I'd next be trying something like this:



That is a 14mm combination wrench and the box end has only SIX points.  If you use an open end wrench, or even a 12 point box end wrench, you stand a good chance of perhaps stripping the head on a stubborn drain plug.  Don't be afraid to rap on the end of said wrench with a hammer a few times (after making absolutely sure that the business end of said wrench is squarely and fully engaged with the head of the drain plug).

Here's what I've used for a long time on that drain plug with great success:





14mm GearWrench....it's the shizz!

Good luck!