I use a cow's knee along with a light wipe of bear grease on the lip of the pan, and the barrel side of the frizzen. Not much is needed. Yesterday , while walking over a beaver pond, I crossed a beaver run where the ice had thinned and I fell through. I rolled out of it, but I , my shot pouch
and my smoothbore took a dunking. Once I got on firm ground, I loosened the cow's knee, inverted the barrel to drain it, brought the lock to full cock and fired the gun before the soaking had a chance to take full effect. Some water had damped the paper cartridge along with a bit of the powder just below it, but the gun did go off. I used to grease my cartridges but no longer do that, but I imagine that if I had a well oiled patch or a greased paper wad, the charge would have been altogether OK.
PS. The walk home sucked