I guessed as much. I've seen olive oil darkening the metal of our flintlocks when used as preservative.  Yet, its better to have a darkened leather than no leather at all...: ) 
 
Now, since the weapon is curved. I need to find a pliable thin container. Or a plastic tube/conduit than can be capped at its bottom end. Not too large, or I will need too large a volume of oil. 
 
Gotta visit Home Depot, and get creative as I look at the stuff. 
 
Best 
 
Manuel
		 
		
		
		
		
		
		
		
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