The above are only partly correct -- more details:
Back in the '60s, when most gas was leaded, Amoco had this special super premium which was not leaded and was therefore safe for some uses where leaded was not, and it also was much less likely to foul plugs in motors which had a severe plug fouling problem, such as the early Porsche 911 (I had a late '66 for a while in the '70s) and Ferrari V12 motors of the pre-smog control era, so it was much sought after by owners of high-performance machinery, including modified American "super" cars. I doubt that it would be any different from the current 93 octane unleaded in practical applications, if it were still on the market, except that some of the other additives that Amoco used instead of lead have now been banned, too.
Addendum: Amoco's early unleaded premium is NOT the same as the "white gas" meant for lanterns, camp stoves, and torches, which was a form of light distillate, similar to the cheap fuel sold for specially equipped farm tractors during the Depression and WWII years. It was almost as dangerous to use the Amoco premium for those purposes as any other gasoline because of the explosion danger and the other additives.
Last edited by Fimum Fit; 10-01-2002 at 03:52 PM.