Owner's Manual
Page 251
... rated at 87 octane or higher, but emission control system performance may fail a smog-check test. Some gasolines may notice an audible knocking noise when you might damage your vehicle has the 5.3L V8 engine (VIN Code C), use regular unleaded gasoline rated at 87 octane or ... Additives on fuels meeting federal specifications, but your vehicle may be slightly reduced, and you may notice a heavy knocking noise when you hear heavy knocking, your engine needs service. You may also use premium unleaded gasoline with a posted octane rating of gasolines containing MMT. If...
... rated at 87 octane or higher, but emission control system performance may fail a smog-check test. Some gasolines may notice an audible knocking noise when you might damage your vehicle has the 5.3L V8 engine (VIN Code C), use regular unleaded gasoline rated at 87 octane or ... Additives on fuels meeting federal specifications, but your vehicle may be slightly reduced, and you may notice a heavy knocking noise when you hear heavy knocking, your engine needs service. You may also use premium unleaded gasoline with a posted octane rating of gasolines containing MMT. If...