tu_79
Deity
You have to know oil mining too. This is a recent change, the tech where oil is revealed is no longer the same that teaches how to extract it. Dig a little through the techs and you'll see which one you need.How does the City State diplomatic mission “improve a resource” work? I am the ally of the CS, have researched the necessary tech, have the appropriate funds, but the mission is grayed out. It is an oil resource with a village on it.