But where has all the oil gone?

Streetwiseguy said:

That might have an oil ring expander overlapped.

Ask me how I know..

Tell me more about this? Fairly sure I did everything correct, but I've been wrong before.

Some sets of rings are quite easy to not have the end of the expander butt,  and the ends overlap instead.  Then the oil rings themselves don't really have any tension on them,

Did your expanders have a little plastic insert at each end of it?  Those are really hard to get wrong. I did a Volvo B21 a few years... a bunch of years ago, and that particular set of rings had expanders that would overlap 3/4 of the time, as it happens.

In reply to Streetwiseguy :

Great.  Now I am paranoid about literally every short block I have assembled, including the 2.4 Volvo in storage and the 2.3 Audi in the garage.  That's ten expanders I could have screwed up that I have every excuse to pull apart again!

In reply to Streetwiseguy :

According to this they had that little bit.  I'm not 100% sure I remember them, though.  I'll dig through pictures and see if I have any of piston ring assembly.

https://www.amazon.com/Sealed-Power-E229X-Piston-Ring/dp/B000C7NLF2

Welp.  No help.  Expander in on the right without the rings, rings in on the left.  No view of the thingie.

Still not found the issue, but the drive to and from lunch reminded me of something that happened this morning.
Was headed down to work today on the interstate. Truck felt weird and has for a week or so, down on power, barely holds what speed I set it at without me getting into the loud pedal, just... off.  Not right.

About 15-20 minutes into the drive it kinda burped under its breath and then everything was fine. Power returned, can hold speed, can pass people again.

Really damn weird. Trying to think through what it might've been and I'm coming up blank.  Wondering if it finally sucked down the automotive equivalent of a snot rocket after being sick for a while.