2007 GMC Envoy Owner's Manual - Page 382

Your vehicle has an airbag system. Before attempting to do your own service work, see Servicing Your Airbag-Equipped Vehicle on page 88. You should keep a record with all parts receipts and list the mileage and the date of any service work you perform. See Maintenance Record on page 521. Fuel Use of the recommended fuel is an important part of the proper maintenance of your vehicle. To help keep your engine clean and maintain optimum vehicle performance, GM recommends the use of gasoline advertised as TOP TIER Detergent Gasoline. Adding Equipment to the Outside of Your Vehicle Things you might add to the outside of your vehicle can affect the airflow around it. This may cause wind noise and affect windshield washer performance. Check with your dealer before adding equipment to the outside of your vehicle. Gasoline Octane Use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, you may notice an audible knocking noise when you drive, commonly referred to as spark knock. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If you are using gasoline rated at 87 octane or higher and you hear heavy knocking, your engine needs service. 382