1994 Buick LeSabre Owner's Manual - Page 217

Fuel Use regular unleaded gasoline rated at 87 octaneor higher. It should meet specificationsASTM D4814 in the U.S. and CGSB 3.5-92 in Canada. These fuels so should have the proper additives, 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 into your vehicle's filler neck. Be sure theposted 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. What about gasoline with blending materiaIs that contain oxygen (oxygenates), 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 is more than5% methanol is bad for your vehicle. Don't use it. It can corrode metal parts in your fuel systemand also damage plasticand rubber parts. That damage wouldn't be covered under your warranty. And even 5% at or less, there must be "cosolvents" and corrosion preventers in this fuel to help avoid these problems. 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 acceleratingor 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.