tree91!
The first and easiest thing, in my opinion, would be to spray that engine with an emulsifier, like 'gunk' or other product, then use a high pressure washer to get it good and clean. Take it for a slow drive (so you don't get blowback) for a couple of blocks, then have a look. We used to do something like that with airplane engines. Washed them down with 'varsol' then ran them up to find out where the leak was.
If that doesn't produce anything then-----somebody else will have an idea.
Had a problem like that with a D---e product. Small leak making a big mess on the driveway! Finally found the oil pressure transmitter leaking after washing the engine down!
