What is this hose?
 

Chasing down an oil leak, the underside of this hose seems a little wet with oil, actually the entire hose looks wet. This is looking down on the top of the engine in the right back corner of the exposed engine.

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It looks like the oil fill tube. It carries motor oil from the trunk fill to the engine.

Engine oil filler tube. Usually rubs against the body as it passes under the edge of the engine bay opening at the bottom right of your picture. After the ribbed part. The joints also tend to leak.
When I replaced mine I wrapped the male end of the pipe joint with one or two wraps of masking tape then slide the joint together. No more oil leaking at the joints.

+1 oil fill tube. This tube can collapse and crack due to excessive vacuum caused by an AOS failure. Crack can create a vacuum leak and oil leak when filling.

This effort is in trying to see where the cause of fresh oil spots on garage floor after IMS DOF installation. I've not been able to identify the source of the leak. This pic is the DOF - oil line from above is dry, so it's not somehow coming from above and running down the line, but that is what looks to be happening here. I've completely dried this area of all signs of oil and run the car while jacked up to see if it's actually coming from this connection, it is not. Going to take the car out for a brisk run and inspect again.

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At idle this connector/oil line would not leak, but a 5 min ride obvious the connector is leaking and I believe the oil line is too. Pic of connector below. Thanks all.

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