Hey guys the reason why its a mystery is cause I havent looked into it at all. Put long tube headers on my V6 and noticed some oil on the passenger side, never noticed anything coming out of my exhaust so I was never too concerned. I assumed it was a valve cover gasket and was getting around to addressing the leak now. Today I went out and took a few pictures to try to confirm the leak was indeed the valve cover gasket and im still not 100% as the valve cover connection to the head looks dry, but the oil is still below it/above the headers. It looks like maybe the leak is coming from the bolt holes (not sure if they are through holes or not). Hopefully someone way more knowledgeable can more easily tell from the picture I attached. Thanks.