How about getting Oil from bears for cooking?
Also it could be from sunflower seeds.
Not a big problem just adding a new ID and
This could be the logic
The drops from a bear could be randomized between leather and oil.
The oil can be harvested from a farm
The house that contains oil will increase any food calories by a % (like 10%)
This new item will increase the travels from the barn to the house, (cost of time)
The ammount of oil decreases everytime somebody eats in the house.
The Oil can be used later for future weapons, vessels, carts, for secondary products, etc.