1998 Buick Century Owner's Manual - Page 263

Fuel You can be injured and your vehicle could be damaged if you try to do service work ona vehicle without knowing enough about it. Be sure you have sufficient knowledge, experience, the proper replacement parts and tools before you attempt anyvehicle maintenance task. Be sure to use the proper nuts, bolts and other fasteners. "English" and "metric" fasteners canbe easily confused. Ifyou use the wrong fasteners, parts can later break or fall off. You could be hurt. Use regular unleaded gasoline rated at 87 octane or higher. At a minimum, it should meet specifications ASTM D48 14 in the United States and CGSB 3.5-M93 in Canada. Improved gasoline specifications have been developed by the American Automobile Manufacturers Association (AAMA) for better vehicle performance and 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 is at least 87. 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. and If you're using fuel rated at 87 octane or higher you hear heavy knocking, your engine needs service. But don't worry if you hear a little pinging noise when you're accelerating or driving a hill. That's normal, up and you don't have to buy a higher octane fuel to get rid of pinging. It's the heavy, constant knock that means you have a problem. Adding Equipment to the Outsideof 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 beforeadding equipment to the outside of your vehicle. 6-3