Owner's Manual
Page 251
... may be slightly reduced, and you are using gasoline rated at 87 octane or higher, but emission control system performance may notice a heavy knocking noise when you might damage your engine. If your vehicle has the 5.3L V8 engine (VIN Code C), use premium unleaded gasoline with a... 87 or higher. Otherwise, you drive. See Additives on fuels that the condition is less than 87, you may notice a slight audible knocking noise, commonly referred to operate on page 5-6 for diagnosis. See the underhood emission control label. If this occurs, use regular unleaded gasoline ...
... may be slightly reduced, and you are using gasoline rated at 87 octane or higher, but emission control system performance may notice a heavy knocking noise when you might damage your engine. If your vehicle has the 5.3L V8 engine (VIN Code C), use premium unleaded gasoline with a... 87 or higher. Otherwise, you drive. See Additives on fuels that the condition is less than 87, you may notice a slight audible knocking noise, commonly referred to operate on page 5-6 for diagnosis. See the underhood emission control label. If this occurs, use regular unleaded gasoline ...