At a minimum, gasoline should meet ASTM specification D 4814 in the United States or CAN/CGSB-3.5 or 3.511 in Canada. Some gasolines contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT).
We recommend against the use of gasolines containing MMT. See Additives for additional information.
Gasoline Octane
California FuelChevrolet Cobalt Service & Repair Manual. Emission Control System Inspection
Caution: Do not remove any
component of the engine emission control system. Operating the engine without
the engine emission control system intact will reduce fuel economy and engine
ventilation. This will weaken engine performance and shorten engine life.
The vehicle ...