Yes the lead is oily. When you say it 99% the gasket, you mean the cam cover gasket?
Yeah the little bit that runs down the middle round the plugs is gone if the lead is oily on the end.
Do yourself a favour and get a genuine gasket kit, I always use some sealant around the cams makes sure if someone else has that you pick it off first.
The oil if left will feck your leads so dont put it off
