Advances in automotive engine design saw major steps forward during the decade of 1910-1920. Early two-cylinder and four-cylinder designs gradually gave way to six-cylinder in-line engines. As early as 1915 Cadillac offered a V-8 engine in certain models. Engines development, however, was hampered by the lack of availability of high octane fuels necessary in developing higher compression ratios. The petroleum industry experimented with a number of blends and additives to gasoline in an attempt to create a fuel of higher anti-knock capability. Of the early additives, a blend of benzene and gasoline, marketed as "Benzol" offered the most promise.
In 1915 a small Baltimore refiner-marketer, critically short of crude supplies, developed a high octane benzol fuel they named "Amoco-Gas," taking an acronym of the corporate name, American Oil Company. Availability of the fuel was somewhat hampered by the company's limited resources and crude oil supplies, and it would be nearly ten years before Amoco-Gas was available outside of a very limited area. The first effort by a major gasoline marketer to introduce a high octane gasoline came in 1922 when Standard of Indiana introduced "Solite," a gasoline with a higher specific gravity (the method for determining octane rating was not established until 1929) than Standard's "Red Crown."
In early 1923, the General Motors Research Labs at Dayton, Ohio began testing the addition of tetraethyl lead to gasoline. Marketing experimentation began when GM teamed with Dayton Independent Refiners Oil Company to introduce an "ethylized" gas, blending tetraethyl lead with gasoline at the pump. The experiment was quite successful and in September 1923, GM teamed up with Standard of Indiana to introduce Ethyl gasoline on a large scale. The following August, GM and Standard Oil of New Jersey formed the Ethyl Gasoline Corporation to franchise the Ethyl additive to gasoline marketers worldwide. The ink had hardly dried on this agreement when lead poisoning deaths in the Ethyl plants brought about a moratorium of the sale of "ethylized" gasoline until further study of potential harmful effects could be determined.
After over a year of study by the U.S. Surgeon General, Ethyl Gasoline was reintroduced, with some restrictions on handling of the tetraethyl lead additive. With the reintroduction of Ethyl, every refiner meeting the Ethyl franchise requirements quickly signed on. Those who were deemed ineligible, for one reason or another, quickly introduced their own premium grade products in order to compete with Ethyl. Thus, in a period of about two years, virtually every marketer began offering at least two grades of gasoline. Those marketers that had, prior to the introduction of Ethyl offered a premium grade product, possibly a benzol blend or an "aviation" grade (Aviation being a common trade name for these non-ethyl premiums in the 1920s) often continued to market this product alongside their new "Ethyl." No tetraethyl lead could be added to any regular grade product until terms of the Ethyl franchise agreement were modified in 1933.
Among major oil companies of this era, Standard Oil remained a single grade marketer, introducing "Blue Sunoco" in 1928 as a non-ethyl premium fuel sold at regular grade prices. Even Amoco, pioneer in high octane non-leaded fuels, offered regular grade products, originally "American Strate" and "Orange American Gas."
