Friends:
I am perplexed that I can't locate the source of an oil leak on 2006 S40, T5. The leak is a small drip once in the morning, 1-2 quarter size drops. About 75K miles on vehicle and have had it for 2+ years, using Mobil1.

The oil residue is located to the left side of the turbo (looking over the engine) , between the turbo and the passender wheel. When I remove the skirt, I see drip where my blue flashlight is located. I have been underneath the vehicle 3 time and can not locate the source. Even letting it run for 30 minutes, saw no source.

I can see nothing from top side at all.

Any advice on possible culprets