I recently changed the oil in my 3.5L, and I noticed an oily residue all over a plug near the drain plug of the oil pan. I'm guessing that this is the sensor for the "change oil" and "low oil" lights. I know oil shouldn't be escaping from there, so my question is: What should I do?
I was told that I should take my car to a dealership by a mech. to have it checked out. I know if I do that "something" will be wrong and there goes my arm. Any input would be greatly appreciated.

Start by cleaning it up and see if it comes back. This area is also prone to road grime and other gunk. If you are lucky then nothing at all is leaking. If you are unlucky then it will indeed be leaking.

Hi
I too find my sensor to be gunked up. However I park in my garage over a concrete floor and have never had any leaking. I simply clean it off when I change the oil. So I'm not too worried.

usually dealerships overcharge.