I agree with this. I know you already said no when I 've asked you about this Bers, but oil tend to be an issue , like food used to be. Most of the industrial units and military buildings require a lot of oil. And to send army to attack we need almost the same amount of food and oil. That means a lot! Derricks are limited at level 10, which is very few. May I suggest you to increase the number of the levels? Also, some fertile Oil spots would be nice on the map. There are for food, why not for oil, considering that we need it too to send the army out?
Also, Oil is considered as global ressource? If yes, why is not included in gold and silver bonuses? If not, why so much oil is required in industrial age? As a secondary ressource must not be so important imo. Thanks