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.
Chevrolet Cobalt Service & Repair Manual. Engine Rebuild Specifications
Cylinder Head, Valve Guide, & Valve Seat
All Measurements Given In Inches
Unless Otherwise Specified
Engine (VIN) 1
Year
Cylinder Head Warpage Limit
Cylinder Head Height/Thickness
Valve Guides
V ...