1995 Buick Riviera Owner's Manual - Page 214

But don't worry if you heara littlepinging 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 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 foryour 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. Gasolines for Cleaner Air Your use of gasoline with deposit control 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 partfor cleaner air. Many gasolines are now blended withoxygenates. General Motors recommends that you usegasolines with these blending materials, such as MTBE and ethanol. By doing so, you can help clean the air, especiallyin those parts of the country that have high carbon monoxide levels. In addition, some gasoline suppliers are nowproducing reformulated gasolines. These gasolines are specially NOTICE: designed to reduce vehicle emissions. General Motors Fuel thatis more than 5% methanol is bad for recommends that you use reformulated gasoline. By your vehicle. Don't use it. It can corrode metal doing so, you can help clean the air, especially in those parts in your fuel system and also damage plastic parts of the country that have high ozone levels. and rubber parts. That damage wouldn't be You should ask your service station operators if their covered under your warranty. And even 5% or at gasolines contain deposit control additives and less, there must be "cosolvents" and corrosion oxygenates, and if they have been reformulated to preventers in this fuel to help avoid these reduce vehicle emissions. problems. 6-5