What happened to gasoline in the mid 1970s?

I don't see where variable octane was mentioned.

Most stations had different grades of fuel and you could select regular, super, or premium each with a higher octane rating than the last.

They all had different names for each. IIRC Sunoco was 220, 240, 260.

Some stations had different pups for each blend, some had dial selectors on the same pump.