1997 Buick Regal Owner's Manual - Page 279

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. Checkwith to your Buick dealer before adding equipment the outside of your vehicle. If you have the 3800 Supercharged engine(VIN Code l), use premium unleaded gasoline rated at 91 octane or higher. With the 3800 Supercharged engine, in an emergency, you may be able to use a lower octane -- as low as 87 -- if heavy knocking does not occur. If you are using 91 or higher octane unleaded gasoline and you hear heavy knocking, your engine needs service. At a minimum, the gasoline you use should meet specifications ASTM D48 I4 in the United States and CGSB 3.5-M93 in Canada. Improved gasoline specifications havebeen developed by the American Automobile Manufacturers Association (AAMA) for better vehicle performanceand engine protection. Gasolines meeting the AAMA specification could provide improved driveability and emission control system protection compared to other gasolines. Be sure the posted octane for premium is at least 91 (at least 89 for middle grade and 87 for regular). If the octane is less than 87, you may get a heavy knocking noise when you drive. If it's bad enough, it can damage your engine. Fuel The 8th digitof your vehicle identification number (VIN) shows the code letter for your engine.You will find the VIN at the top left of your instrument panel. (See "Vehicle Identification Number" in the Index.) If you have the 3800 engine (VIN CodeK), use regular unleaded gasoline rated at 87 octaneor higher. If you're using fuel rated at the recommended octane or higher and you hear heavy knocking, your engine needs service. But don't worry if you hear a little pinging noise when you're acceleratingor driving up a hill. That's normal, and you don't have to buy a higher octane fuel to rid of pinging. It's the heavy, get constant knock that means you have a problem.