Oil leak

Can you tell me where this oil is leaking from?

That appears to be a leaking valve cover gasket to me.

Clean it all up. Spray it with a white powdery antiperspirant spray. then the brown stain in the white powder will become obvious as to its source.

Followed by the usual cautions of not "fixing" it by over-tightening the bolts and stripping the center one.

Looks like a pre-'75 head? If those are exposed stud tubes that I see through the head fins, you may have oil leaking around the tubes, between the steel tube and the aluminum. The O-rings under the rocker tower sleeves are supposed to control that. BMW no longer sells the right O-ring for that spot, but I can dig the dimensions out if that is the problem.

You need to pull off one rocker at a time, slide the sleeves off the towers, and see if you have O-rings under there.

Some of this may be described on my website.

Thanks for the help. I've replaced the valve cover, cleaned it up and will watch it. If it's still leaking, I'll check the o rings.