Where to get crude oil from?
Tips to Get Crude Oil or Any Resource
It is mined in some cities, such as iron ore. You can also buy it on the world market.
The game is semi-random. Towns and overall map is static but what resources are found where are randomized to a degree. If you have no oil you need to buy some via the trading screen and make it gets shipped to where your refinery is so it can be processed into fuel.
Alternative, or “later” you can conquer a town somewhere on the map that has oil as its resource.