I have a 2000 Mercury Grand Marquis oil leak but I'm unable to locate the leak.
I think is started after my last oil change. I was doing some spirited driving that day after the oil change and that's when I noticed an oil smell coming through the air vent in my car but, only when I stop at a light.

 

Check the whole oil lining. It is not difficult to check. But for viewing it properly you will have to get down to vehicle.