Wrong.
See post 20.
That is an old school from the days of the oil companies using tetraethyl lead to raise the octane rating.
Back in the early days most engines were very low compression. You would not believe how low. 4-5 to 1 or less. A high grade of kerosene would run most Model As. Read some of the horror stories about the “pool gas” from England after the war.
Just my experience with my Toyotas.