What with gas prices (
) the way they been going up lately, I would like to know which grade of gas Mustangs need:
Originally, my Stang had a 289 2 barrel carb
Now, it has the same engine with a EB intake manifold and 650 CFM 4 barrel Holley carb.
I've been using premium (octane 91, as I remember). Could I use a lower octane gas?
What engine or other parameters dictate which grade of gas to use?