[Bob ONeill]

I have a bad leak at the rear main seal. I will need to remove the tranny to deal with it but.... I mention this to suggest that you may have the same problem. Otherwise the head gasket can 'seep' as can the valve cover gasket.

Since it's a turbo it could also be the oil feed or return lines to/from the turbo.

Otherwise it's a seal or gasket somewhere.