Cam cover gasket.

[Ben Jay]

D seal perhaps...?
Give it a good ol' clean, little bit of petrol on a rag cleans it up well before you apply the new gasket.

I often get it sandblasted and a coat of paint, works well, just some heatproof stuff does the job well

it had a new d seal a couple of months ago. so no need to change right? might get some silcone sealant around the seat to stop a boost leaks.