I rigged an oil extractor from an old chemistry lab vacuum pump, a 5 gallon pail with a gasketed lid and suitable lengths of hose. One hose connected the pump's suction port to the pail and the other was a length of 1/4" hose which reached down the dipstick tube.

It ran slowly and when I closed the throttling orifice to increase the suction, the sides of the pail collapsed so I know the system was quite free of air leakage.
15 torturous minutes of extraction yielded barely a pint (16 oz.) of oil. I was stumped.

The oil I had collected resembled semi-dissolved jam. 'Twas all shifty and wavy, not like plain, familiar oil sloshing in the bottom of a pail.
I had a heart attack.

Pulling the drain plug saw the oil drain normally.
The pail I had used for my extractor was clean. It had been 1/4 full of floor cleaner but rinsed out perfectly.

I must try this extractor again as I need it for another car. This was an experimental run.

Perhaps the 1/16" inner diameter is simply not big enough for effective oil suction.
I'm still wondering about the appearance of the "drawn pint" because it was from a dealership's oil change. They used a Volvo filter alright but heaven only knows what kind of oil. Some kind of "motor honey" quieting agent came to mind.

Cheers and Happy August!