Exactly how much oil do you think is being burned to spin a turbine?
I've been in most of the base line power plants in the upper midwest and have yet to see anything rated above 50MW burning anything but coal or uranium. Other than natural gas, the only petroleum products I've ever seen burned is kerosene (J4) in GE jet turbine backups. The gas burners' output watts hardly rank as "base line". Its why they're called "peakers".
GE offers the widest range of heavy duty gas turbines available, ranging from 26 to 480 megawatts