Engine head oil leak.

[spldart]

I noticed some dried on oil on some of the cooling fins of the jug when I bought
this bike.
Then I got it running and I noticed that it makes burning oil smells coming
straight up off the motor when I came to stops.

However... I haven't had to add any oil and there was no excess oil or soot at the
exhaust pipe.

I have finally found the oil leak. It's at the seam between the upper and lower
cylinder head.
Question:

Does this take a gasket or can I just put some brand name blue silicone on the
junction and reassemble?