1995 Oldsmobile Achieva Owner's Manual - Page 212

Fuel Use regular unleaded gasoline rated 87 octane or at higher. It should meet specifications ASTM D4814 in the United States and CGSB 3.5-92 in Canada. These fuels should have the proper additives, you should not so have to add anything to the fuel. In the United States and Canada, it's easy to be sure you of get the right kind gasoline (unleaded). You'll see UNLEADED right on the pump. And only unleaded nozzles willfit into your vehicle's filler neck. Be sure the posted octaneat least 87. If the octane is 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 usingfuel rated at 87 octane or higher and you still hear heavy knocking, your engine needs service. But don't worry if you hear a pinging noise when little you're accelerating or driving up a hill. That's normal, 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. NOTICE: If you try to do your own service work without knowing enough about it, your vehicle could be damaged. 6-2