"Said he can steal pretty much however much he wants."
I'd find a different friend, this one is liable to get you in trouble.
I too worked at an airport in my younger days. Our regular airplane fuel was 101 octane (blue in color), sold for around 1.45, back in the day when premium was about .95. We also sold reugular 87 octane for the smaller 4 cylinder planes such as the Cessna 150 and the little experimentals that would come and go.
Like the others have said, Jet A50 is kerosene, more or less.