1995 Pontiac Bonneville Owner's Manual - Page 218

If you're using fuel rated at 91 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 tobuy a higher octane fuel to get rid of pinging. It's the heavy, constant knock that means you have a problem. What about gasoline with blending materials that contain oxygen (oxygenates), such as MTBE or alcohol? Methanol is methyl or wood alcohol. NOTICE: Fuel that is more than methanol is bad 5% for your vehicle. Don't use it. It corrode metal can parts i your fuel system and n also damage plastic and rubberpark That damage wouldn't be covered under your warranty. And even 5% or at less, there must be "cosolvents" and corrosion preventers i this fuel to help avoid these problems. n 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. 6-5