Not very fluent with circuits but... If I have a oil loading station on one side of a map, and the drop-off on the other side. Connect circuits together. If my tanks on the south side of the map are full (or at a certain amount) then disable the loading station.

I was thinking about a way of re purposing things like barrels. Maybe if I had a bunch of empty barrels I could throw them into a furnace and make it into a steel plate. But make it expensive like 10 barrels to 1 plate or you could make it less so it is not an easy way to get rid of barrels. Maybe ...