Hot Oil smell and oil below air inlet manifold

[adrianlp]

Hi all,Whilst searching for the smell of hot oil from the engine I found a lot of oil around the area shown in the workshop manual image (attached) behind the writing "ignition coils..." Etc. Any thoughts where this could have come from? Could this be rocked cover gasket/seals? Important to add that I sent the temperature into the red when an airlock in the coolant developed because of the hole in the heater core... I am concerned I have done real damage and the oil is the evidence. Any thoughts, please? The engine sounds fine and I have my hands full with the prospect of removing the heater core so I am prepared for trouble...Very grateful for any insight, and anyone who has filmed or photographed a heater core removal, I would love to see how I will be spending a week doubled up with my legs out the sunroof.Adrian