The worst of the oil leak & fumes are more likely to be coming from the hole (see pic) on the back of the block. I believe there should be a rubber bung in it. It's most likely perished & come out ?
I think the hole is there because it has the same block as the turbo engine & that is where the oil return pipe would be from the turbo ?
Not sure, but i think this is what's missing ?
https://www.skandix.de/en/spare-part...block/1021416/