1993 Buick Regal Owner's Manual - Page 217

Fuel Use regular unleaded gasoline rated at 87 octane or higher. It should meet specifications ASTM D4814in the U.S. and CGSB 3.5-92 in Canada. These fuels should have the proper additives, you should not have so to add anything to thefuel. 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 into your 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 fuel to get rid of pinging. It's the heavy, constant knock that means you have a problem. What about gasolinewith blending materials that contain oxygen, such as 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 i more than 5% methanol is bad for s your vehicle. Don't use it. It can corrode metal parts in your fuel system and also damage plastic and rubber parts. That damage wouldn't be covered under your warranty. And even 5% at or less, there must be "cosolvents" and corrosion preventersin this fuel to help avoid these problems. I Gasolines for Cleaner Air Your use of gasoline with detergent additives will help prevent deposits from forming in your engine and fuel system. That helps keep your engine in tune and your emission control system working properly. It's good for your vehicle, and you'll be doing your part for cleaner air. Many gasolines are now blended with materials called oxygenates. General Motors recommends that you use 215