You’ll need to have reached the Busy Town milestone to unlock it. Of the four industry specializations in Cities: Skylines Industries ( farming, forestry, ore, and oil), oil is unlocked last. Step 1: Preparing to Build Your Oil Industry Oil Industry Area Products in Unique Factories.Step 5: Leveling Up to Unlock Buildings.
Step 2: Creating Your Oil Industry Zone.Step 1: Preparing to Build Your Oil Industry.