I've had a "tick" from the motor that could be heard at idle for the last few thousand miles. Kind or subtle, not something most people would ever notice. Maybe 3 ticks per second as a rough guess. I couldn't pinpoint it with a stethoscope from under the hood or under the van. Oil was fresh and pressure was steady.

Two days ago I changed the oil pan gasket and pickup tube O-ring. It never leaked or lost oil. It was just starting to get damp around the gasket but I like being proactive. The O-ring wasn't hard but it fell on the floor when I pulled the tube out rather than staying with the tube or in the hole. Maybe it lost integrity even though it was still soft.

FF to the end of the job as I'm running it and looking for any leaks or other issues. No ticking! Just purring like a kitten. Drove around yesterday and it was still gone.

My guess is that the O-ring was letting some air get through. Any other ideas?