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. Fuel Pressure Relief
1.
Loosen fuel fill cap to relieve fuel
tank vapor pressure.
2.
Remove engine cover.
3.
Remove fuel rail service port cap,
then wrap a shop towel around fuel rail service port.
4. ...