About 45 years ago my brother got his first job pumping gas at an Exxon (then Esso) station on Rt. 22 in NJ. He was told it was the busiest gas station in the United States.
Also said they routinely added regular gasoline to the premium tank, and kerosene to the regular tank.
Most of the fuel treatments which are sold on the shelves of auto parts stores and other retailers are nothing more than kerosene. He may have been cleaning carbs without knowing it.