If the vehicle is certified to meet California Emissions Standards, it is designed to operate on fuels that meet California specifications. See the underhood emission control label. If this fuel is not available in states adopting California emissions standards, the vehicle will operate satisfactorily on fuels meeting federal specifications, but emission control system performance might be affected. The malfunction indicator lamp could turn on and the vehicle might fail a smog-check test.
See Malfunction Indicator Lamp. If this occurs, return to your authorized dealer/retailer for diagnosis. If it is determined that the condition is caused by the type of fuel used, repairs might not be covered by the vehicle warranty.
Chevrolet Cobalt Service & Repair Manual. Cylinder Head Overhaul
It is usually recommended to send
head to machine shop for complete overhaul.
Cylinder head must be cool before
removing it from engine. Cylinder head warpage can result if a warm or hot
cylinder head is removed.
Place clean shop towels over exposed
e ...