Any ideas on what this could be, would be extremely helpful! I've noticed that my '09 Milan V6 AWD will have a small oily spot under it if it sits still for a few days. The substance doesn't seem to have a color but it's somewhat oily in texture with I touch it and rub it between my fingers. When parked, the spot is located under the engine near the driver side wheel/axle area. The last time I took it to the dealership for a full service oil change, I asked them to check it out and they said they didn't see anything.

Thank you!

 

Don't know if your problem is the same as mine but my 2010 Milan FWD V-6 had a similar leak on the driver's side. There's an underbody shield down there that tends to collect stuff. When I parked on my sloped driveway it dripped out.
Turns out there's a TSB on the subject. The dealer fixed the car under the powertrain warranty. :-)
The repair consisted of replacement of the left side halfshaft, bushing and seal.