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. Valve Spring Replace
This procedure is designed to
replace valve spring while head is attached to engine.
1.
Install a suitable flywheel holding
tool in order to prevent crankshaft rotation.
2.
Remove applicable spark plug from cylinder
...