Packard Forum Index » Post-War (1946-54)

Thanks for the input, guys. The concern I have is that today's gasoline bears but a passing resemblance to the "Premium" of 1954: Aside from the addition of lead, "Super" was 100+ octane (those were the days)..and of course, today we have 10%ethanol, and a max of 93 pump octane, which is what I've been using, largely without problem. And it sounds like most are using premium, as well.

In Montana at least, Exxon premium has no alchol, which is a good reason to use it.

You should also know that octane varied over the years. In the thirties high test was about 75 octane, regular about 65. They also sold "straight run" gas with no additives which was 50 or 55 octane.

It was about 1954 and 55 when the heavily leaded, high octane gas became available. That is when compression ratios started soaring. As late as 1951 I don't believe you could buy gas at a gas station that was over 80 octane.

In the sixties regular was 88, hi test 98 and you could get some brands over 100 octane like Blue Sunoco 103 octane.

Was octane calculated and reported the same way thru the years or did some of the methodology change.

this might help then again it confused the heck outta me..

en.wikipedia.org/wiki/Octane_rating

Thanks. It is confusing but if I read correctly, we currently use AKI method but wonder if it was always so. Most everyone else in the world appears to use RON.

Until the mid seventies research octane and motor octane numbers were both legal in the US and both were used, usually the research number appeared on the gas pumps and in gas advertising because it was higher.

Starting in the mid seventies the government mandated a new octane rating, the average of the RON and MON called the anti knock index or pump octane. So today's gas is actually 4 or 5 points better than the numbers indicate, according to the system used in the sixties and earlier.

For a while Mobil tried to promote their own system called "Megatane"but it was mainly an advertising gimmick.