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Gasoline properties have changed considerably since 1908 when the automobile became the principal consumer of gasoline. This paper provides a history of changes in gravity, lead antiknock additive content, antiknock index, volatility, sulfur content, hydrocarbon composition, oxygenate usage, and additives. Today's gasoline has evolved into a high octane, low sulfur product which now has limits on the maximum vapor pressure and contains oxygenates to help reduce harmful emissions. GASOLINE WAS CONSIDERED a worthless by-product of petroleum prior to its commercial development which began no later than 1863. Who discovered it is difficult to establish, but Joshua Merrill may have isolated gasoline in Boston as a result of his efforts to further refine kerosene, the primary petroleum product at that time (1)*. Gasoline was first used in air-gas machines to produce fuel that could be piped and burned in gaslights to illuminate mills and factories.

Additives have been used commercially in the United States (U.S.) since 1923 to enhance the performance of motor gasoline or to solve deficiencies. As time has passed, new additives have appeared and old additives have disappeared. A review of the technical literature and oil industry periodicals was undertaken to determine when an additive was introduced and by what company. A description of the benefits provided or problem solved by the use of each additive is also presented. This paper provides a historical record based on published literature of when, why, and by whom gasoline additives were first used.

A nine-year effort from 1972 to 1981 was undertaken by the Coordinating Research Council Carburetor Test Procedure Panel to develop a laboratory engine test method for evaluating the effects of gasolines on the formation of throttle body deposits. This paper summarizes the test development, discusses effects of engine operating conditions on test severity, gives data on fuel effects, and presents a final test procedure that uses a removable carburetor throttle bore sleeve to permit weighing of deposits. A carburetor visual rating procedure was also developed. The final engine test procedure has proved to be an effective in-house tool for screening fuels and additives. An unresolved problem is poor interlaboratory reproducibility.

Starting August 1, 1979, a one-year gasohol test was conducted by Contra Costa County. A total of 30 county pool cars were on test-15 on gasohol and 15 similar cars on gasoline as a control group. Findings were as follows. There were no fuel-related maintenance problems in either the gasohol or gasoline groups of cars. Cool weather driveability for the gasohol cars was the same or better than gasoline cars. No vapor lock or other hot driveability problems were reported for either fuel. Fuel economy of the gasohol cars was about 5% poorer than that of the gasoline cars. Fuel system deposits with gasohol were increased and differed in character compared to gasoline. Also, the gasohol carburetors showed more inlet needle valve tip wear. However, to date, the observed deposits and wear with gasohol have not caused any apparent problems.

The effects of unleaded gasoline properties on the formation of carburetor deposits were studied by analyzing data from six field tests and by conducting a laboratory engine test program which investigated a wide range of gasoline properties. The results showed that increasing sulfur, nonbasic nitrogen, olefin, and existent gum contents and 10% and 90% evaporation points increased carburetor throttle body deposits. The most practical and economical way to control carburetor deposits is with the use of an effective deposit control additive. Such an additive can also clean up and keep clean critical areas of a new design variable venturi carburetor. Problems of measuring fleet fuel economy are also discussed.

Carburetor throttle body deposits are known to be very critical toward upsetting exhaust emissions and increasing fuel consumption. This study showed that other carburetor areas are just as important. Deposits in the idle air bleed-metering cluster and venturi sections caused sizable increases in emissions and fuel consumption. Because carburetor deposits can cause large deviations from the designed air-fuel metering characteristics, it is extremely important to keep them from forming. Most carburetor detergents work only in the throttle body area. Because upper carburetor deposits were shown to be critical, additives are needed to control deposits throughout the carburetor.