The Oil Pump is the sole machine capable of extracting Crude Oil from underground deposits. Three Oil Pumps are required to keep one Basic Distiller operating at full throughput while it takes only two Oil Pumps to keep one Distillation (Stage I) running continuously.
The Crude Oil resource layer is automatically displayed while attempting to place an Oil Pump. The height of the black black cylinders visually indicates the amount of Crude Oil remaining in a deposit while the numerical amount is shown in the machine's UI details under "Reserve Status". If the Crude Oil deposit underneath gets low, the Oil Pump will give a warning in the warning pane and its extraction speed will decrease greatly.