for whatever its worth and somewhat related.. I've seen where some folks have blown the seals at the turbo and lose oil pressure. Check for leaks near the turbo. Or blown Head Gaskets as well.. I had the experience of adding more antifreeze to my car and not seeing it go anywhere on the ground.. most times my HG blew internally.. and possibly by design.
Sounds silly but got in the habit of checking the oil for any discoloration on the dip stick.. and re-torquing the head every so often after major upgrades.
The simplest recommendation you eluded to early on.. is dropping the pan and cleaning that pick-up tube screen. But use high mileage oil with viscosity that applies to older cars.
Last edited by DC_SAAB; 09-19-2014 at 11:28 AM.