Is there any chance this could be the oil pressure sensor leaking? I had a good leak on my '05 when I bought it last year, and the dealer even noted it was the oil pressure sensor when they were doing the timing belt and water pump.
I changed it with an O'Reilly brand part out of haste, but I'd do OEM if I could go back. It was pretty easy to get to, just behind the filter, but you need a deep 22mm, I think?. As always, my biggest challenge was unclipping the plug connection. I still have another oil leak somewhere, looks like the driver valve cover, but I don't lose a noticeable amount between OCs. I tightened my VCGs bolts with a 1/4 ratchet as some weren't even finger-tight.
It's funny, too, because I had just changed the oil pressure sensor on my '98 and it was the main cause for me losing almost a quart every 1-2 weeks. Fixed my issue.