[Fzeed]

Is this correct? 91 octane?

 

[kt64]

Back in 1972 91 leaded octane was regular. premium began at 95 octane. If I remember right, Shell gas had highest octane at 105. A common premium octane then was 97. No lead began 74-75. Catalytic converters started in '75. I started driving in 1974.