1994 Buick Century Owner's Manual - Page 211

Fuel Use regular unleaded gasoline rated at 87 octane or higher. It should meet specifications ASTMD4814 in the U.S. and CGSB 3.5-92 in Canada. These fuels should have the proper additives, so you should not have to add anything to the fuel. In the U.S. and Canada, it's easy to be sure you get the right kind of gasoline (unleaded).You'll see "UNLEADED' right on the pump. And only unleaded nozzles will fit intoyour vehicle's filler neck. 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. If you're using fuel rated at 87 octane or higher and you still hear heavy knocking, your engine needs service. But don't worry if you hear a little pinging noise when you're accelerating or driving up a hill. That's normal, and you don't have to buy a higher octane fuelto get rid of pinging. It's the heavy, constant knock that means you have aproblem. What about gasolinewith blending materials that contain oxygen (oxygenates), suchas MTBE or alcohol? MTBE is "methyl tertiary-butyl ether.'' Fuel that is no more than 15% MTBE is fine for your vehicle. Ethanol is ethyl or grain alcohol. Properly-blended fuel that is no more than 10% ethanol is fine for your vehicle. Methanol is methyl or wood alcohol. NOTICE: Fuel that is more than methanol is bad for 5% your vehicle. Don't use it. can corrode metal It parts inyour fuel system and also damage plastic and rubber parts. That damage wouldn't be covered under your warranty. And even5% at or less, there must "cosolvents" and be corrosion preventers this fuel to help avoid in these problems. 209