My apologies, and, thank you for the pointer.
There's a gap at the head, where the oil feed is picked up.
Both washers are on, but, it seems as if the oil line is kinked towards the driver side, so there's a gap towards the rear of the car.
As soon as I crank the engine, the leak ensues.
And, in case anyone wonders, the washers are the right fit.
What should I do? Bend the line slightly so it fits flush?