1998 Oldsmobile Aurora Owner's Manual - Page 255

Fuel You can be injured andyour vehicle could be damaged if you try to do service work on a vehicle without knowing enoughabout it. Be sure you have sufficient knowledge, experience, the properreplacement parts and tools beforeyou attempt any vehicle maintenance task. Be sure to use the proper nuts, bolts and other fasteners. "English" and "metric" fasteners can be easily confused. you use If the wrong fasteners, parts can later break or fall off. You could behurt. Use premium unleaded gasoline rated at 91 octane or higher for best performance. You may use middle grade or regularunleaded gasolines, but your vehicle may not accelerate as well. At a minimum, the gasolineyou use should meet specifications ASTM D4814 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 premium is at least 91 (at for least 89 for middle gradeand 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. If you're using fuel ratedat 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 accelerating or driving a up hill. That's normal, and you don't have to buy a higher octane fuel to get of pinging. It's the heavy, constant rid knock that means you have a problem. 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 retailer beforeadding equipment to the outside of your vehicle.