Lost about a quart driving > 500 mi. within the regular oil change (4k miles). No uncommon exhaust/smoke or oil on ground. Took in for oil change and feedback and no issues found. Mentioned that perhaps the rings(?) might be bad, but that would require extensive work.

Noticed on the board that the irregular oil consumption might be caused by oil being sucked around PCV valve and rubber seal? Assuming the shop would've seen this (haven't asked if they checked).

Any ideas??

 

If this started overnight I would monitor it for a few weeks checking it every few days. If it's been a long slow degrade then a compression check may reveal bad rings etc.

 

the shop probably didn't check the pcv valve due to being on the back side of the engine, and at least mine was a real pain to pull out,

and just to clarify, You lost 1qt with in 500 miles after having you oil changed,
did you check the oil the day after your oil change to be sure the shop put 5qts in and not just 4qts by mistake?