Leaking injector

[Surfboy]

I've been running WVO 90% / unleaded 10% for a while now. I went to do my oil change and fuel filter change today and noticed this. There's a large patch of wet oil down the side of the engine underneath as well.

I have given the top two nuts a tweak (14mm and 17mm) and will see how it goes.

What else could be the problem?