Thank you superDave (remember him?) for that thoughtful and complete response.

Your musings about spilling oil reminded me that I had crafted a bizarre plasticized semi-funnel back in my brick days that fit up in there and flowed the oil out and away, as it were. I'll have to do that again.

But my son who is a full time tech says he routinely punches or drills a hole in the bottom of most filters, goes away and comes back later to remove it empty. Perhaps that trick and another bizarre funnel would work together.

This car was driven by a college girl who graduated, and traded back to the indy Volvo specialist lot that sold it. Ironically, the same story had played out for the previous PO, same dealer, different girl, same university. So I doubt she changed the oil herself, and this dealer does no servicing anymore. It may have been a quicky oil change shop.

So net/net considering all data, I'm betting on a poorly installed oil filter or oil pressure sender. It's right in that area, and it's very clean oil. I just ordered some up from IPD, along with spare oil filler cap gaskets. I'm also going to verify the PCV system and famous flame trap.

I don't share your enthusiasm for the belly pan, alas. I'm old as dirt and never saw one until the 90s. I routinely remove them. Except for the 2 decades we lived in yurrup, where it's mandatory for sonic emissions reasons when doing one's yearly tech inspection.