Seasoning is a myth.
They used animal fat because that is all they had.
There is nothing wrong with petroleum products, the idea the they make asphalt in the bore is more myth. Bore butter for instance, is mostly petroleum. It is actually chap stick with oil of winter green, btw.
Something containing water must be used to dissolve the corrosive substances in BP fouling. Simple mechanical action with oil will work but is much more time consuming.
Preserve your bore with whatever modern grease or oil you like. Olive oil or hog fat will invite rust. The only decent non petroleum preservative I know if is lanolin.
