1998 GMC Safari Owner's Manual - Page 265

/r\ C-,TICJ: Fuel . You can be injured and your vehicle could be damaged if you try to do service work on a vehicle without knowing enough about it. 0 Be sure you have sufficient knowledge, experience, the proper replacement parts and tools before you attempt any vehicle maintenance task. 0 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 regular unleaded gasoline rated 87 octane or at higher. At a minimum,it 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 at least87. If the octane is is less than 87, you may get a heavy knocking noise when you drive. If it's bad enough, can damage your engine. it Adding Equipment to theOutside of Your Vehicle Things you might add to the outside your vehicle can of affect the aifflow around it. This cause wind noise may and affect windshield washer performance. Check with your dealer before adding equipment the outside of to your vehicle. If you're usingfuel rated at 87 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 get r of pinging. It's the heavy, constant knock that means you have a problem. 6-3