Today I went looking for oil leak(s). There's a lot in front, but no obvious source (like the front main seal). I degreased some of the area, especially around the timing gear cover and the lift pump. Luckily the gear cover isn't the problem.
But the turbo drain I already knew was leaking badly. After removing the airbox, I started feeling underneath and was unpleasantly surprised to feel that the rearmost of the two nuts securing the turbo to the pedestal was
gone. The other wasn't so tight either. Well, that explained the leak!
A couple of minutes with a magnetic probe and I found the wayward nut on the intake by #7 port, and was able to get it back on with fingertips and a 9/16" box-end wrench. The real fun came in tightening it (which I suspect is why it was so loose it came off in the first place). I didn't want to heat-and-bend a wrench into the required interesting shape to clear the compressor housing, injection lines, etc. I was able to tighten that nut by using two different box-end wrenches, 1/12 turn each. The other nut was a little easier but not all that much. Anyway they're good and tight now.
I fired up the engine and let it run at fast idle for several minutes, and couldn't feel any new oil on the pedestal. I also topped off the oil to the middle of the crosshatched area on the dipstick, so I can see how fast it disappears. Think I've got it fixed. I hope