There was oil around the exhaust side of the cylinder head cover gasket and also in one of the spark plug tubes so time to replace this gasket.
I last did one of these on my first E30 318is and that didn't go well because I discovered that most of the threads were damaged and needed to be fixed.
The cover came off easy and I cleaned up the surfaces and put on the new gaskets. As I tried to put it back on the engine the gasket fell off so I tried a little liquid gasket to hold it in place.
This worked well but it was very hard to tell if the half-moon shaped pieces at the rear went into position. Using a mirror they seem okay, so hoping for the best.
With a torque wrench set to 10 nm the bolts seemed to be too tight and one felt to be stripping so I stopped on that one and stopped using the torque wrench and just used my best judgement.