1995 Buick LeSabre Owner's Manual - Page 205

Fuel Use regular unleaded gasoline rated at 87 octaneor 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, SO you should not have to add anything to the fuel. In the United States 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. What about gasoline with blending materials 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. Ethnnol is ethyl or grain alcohol. Properly-blended fuel that is no more than 10% ethanol is fine for your vehicle. M e t h z o l is methyl or wood alcohol. 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 damageyour engine. NOTICE: Fuel that is more than 5% methanol is bad for 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% or at 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 engineneeds 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 tobuy a higher octane fuel to get rid of pinging. It's the heavy, constant knock that means you have a problem. 6-3