Chevrolet B7 2001 Owner's Manual page 115

Fuel (Gasoline Engine)
If your vehicle has a diesel engine, see "Diesel Engine
Fuel" in this section. For vehicles with gasoline engines,
please read this.
Use regular unleaded gasoline rated at 87 octane or higher.
It is recommended that the gasoline meet specifications
which were developed by the American Automobile
Manufacturers Association (AAMA) and endorsed by the
Canadian Motor Vehicle Manufacturers Association for
better vehicle performance and engine protection.
Gasolines meeting the AAMA specification could provide
improved driveability and emission control system
performance compared to other gasolines.
4-4
Canada Only
Be sure the posted octane is at least 87. If the octane is
less than 87, you may get a heavy knocking noise when
you drive. If it's bad enough, it can damage your engine.
In Canada, look for the
"Auto Makers' Choice"
label on the fuel pump.