It's not like lead-free and eathanol-free gas is devoid of anti-knock agents... for much of those decades MTBE was used which was part of a groundwater contamin

It's not like lead-free and eathanol-free gas is devoid of anti-knock agents... for much of those decades MTBE was used which was part of a groundwater contamination scandal. Wikipedia has an interesting article on the subject @ https://en.wikipedia.org/wiki/Antiknock_agent https://en.wikipedia.org/wiki/Antiknock_agent