Camshaft cover Gasket
The only oil-bearing item above the head is the camshaft cover gasket. So that's a possibility. We do those from time to time. Other than that, ther'es not much more to pick at from the description. This is the same design cam cover Jaguar has used for years, and we do a fair amount of those. I'm surprised we don't do more of them due to oil leaking past the orings around the plugs causing a misfire, but I'm sure that is coming.
As these vehicles age, I'm sure I'll hear more and more, can I do it myself? I think if you have a fair amount of mechanical knowledge and you had the pertinent torque info from GTR, most people could do it.
I should probably not answer this stuff before I finish the first cup of coffee.
The newer generation of vehicles has been pretty interesting...