2009 Chevrolet Impala Owner's Manual - Page 257

Keep a record with all parts receipts and list the mileage and the date of any service work performed. See Maintenance Record on page 6-15. Adding Equipment to the Outside of the Vehicle Things added to the outside of the vehicle can affect the airflow around it. This can cause wind noise and can affect fuel economy and windshield washer performance. Check with your dealer/retailer before adding equipment to the outside of the vehicle. The 8th digit of the Vehicle Identification Number (VIN) shows the code letter or number that identifies the vehicle's engine. The VIN is at the top left of the instrument panel. See Vehicle Identification Number (VIN) on page 5-96. If the vehicle has the 3.5L V6 engine (VIN Code K) or the 3.9L V6 engine (VIN Code M), you can use either unleaded gasoline or ethanol fuel containing up to 85% ethanol (E85). See Fuel E85 (85% Ethanol) on page 5-8. In all other engines, use only the unleaded gasoline described under Gasoline Octane on page 5-5. Gasoline Octane For all vehicles except those with the 5.3L V8 engine (VIN Code C), use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, you might 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, the engine needs service. Fuel Use of the recommended fuel is an important part of the proper maintenance of this vehicle. To help keep the engine clean and maintain optimum vehicle performance, we recommend the use of gasoline advertised as TOP TIER Detergent Gasoline. 5-5