6-3CAUTION:You can be injured and your vehicle could bedamaged if you try to do service work on avehicle without knowing enough about it. Be sure you have sufficient knowledge,experience, the proper replacement partsand tools before you attempt any vehiclemaintenance task. Be sure to use the proper nuts, bolts andother fasteners. “English” and “metric”fasteners can be easily confused. If you usethe wrong fasteners, parts can later breakor fall off. You could be hurt.Adding Equipment to the Outside ofYour VehicleThings you might add to the outside of your vehicle canaffect the airflow around it. This may cause wind noiseand affect windshield washer performance. Check withyour dealer before adding equipment to the outside ofyour vehicle.FuelGasoline OctaneIf your vehicle has the 5.3L engine (VIN Code T), useregular unleaded gasoline with a posted octane of 87 orhigher. If the octane is less than 87, you may get a heavyknocking noise when you drive. If it is bad enough, itcan damage your engine. A little pinging noise whenyou accelerate or drive uphill is considered normal.This does not indicate a problem exists or that ahigher- octane fuel is necessary.If your vehicle has the 6.0L HO engine (VIN Code N),use premium unleaded gasoline with a posted octane of91 or higher for best performance. You may also usemiddle grade or regular unleaded gasoline rated at87 octane or higher, but your vehicle’s acceleration maybe slightly reduced. If the octane is less than 87, youmay get a heavy knocking noise when you drive. If it isbad enough, it can damage your engine.
