I have a 2.2l 2007 ion and I changed the oil about a week ago and now I've noticed oil spots on the drive way so I popped the hood and found a little puddle of oil on the transmission and around the oil filter area. I though it was the oil filter but I've checked it multiple times and the filter and o ring are all good so I have no idea where this leak is coming from.

 

I I would start by cleaning off all of the existing oil mess. Then start the vehicle allow it to idle in park or neutral if manual transmission. With the hood up if you can see where the puddle was forming on the transmission you should be able to see where the oil is seeping from. I'm not sure how you are checking the seal and filter. It either seals or it doesn't. I do not know the location of components under the hood for a 2.2 ion. Is it possible this puddle was formed when you refilled the engine with oil and spilled some which found its way down there and is now slowly running its way off onto the ground? Also is the oil level in the engine actually dropping and if so at what rate? That sounds like a silly question but if it is truly leaking the level on the dipstick should be dropping.

 

I think the pcm mounts over the top of the transmission. Ions have electric power steering so there should not be anything on the ends of the camshafts. The valve cover can still leak and I have had cheap aftermarket gaskets leak. 10 year old oem gaskets can leak also. I find it odd that the car did not leak before the last oil change. The only way the oil filter can leak onto the transmission is from the oil filter cap o-ring. It would have to spray up and back to get to the transmission. However spilled oil would run down to the transmission and the filter area. The oil pressure switch is pretty low and behind the starter on the 2.2. Like Derf says wash it off and see what comes back.