1994 Oldsmobile Achieva Owner's Manual - Page 174

Service &Appearance Care 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 noisewhen 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 theheavy, constant knock that means you have a problem. All Engines: What about gasoline with blending materials that contain oxygen (oxygenates) such as MTBE or alcohol? MTBE is "methyltertiary-butyl ether.'' Fuel that is no more than 15%MTBE is fine for your vehicle. Ethanol is ethyl or grain alcohol. Properly-blended fuelthat is no more than 10% ethanol is fine for your vehicle. Methanol is methyl or wood alcohol. ) 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 also and damage plasticand rubber parts. That damage wouldn't be covered under your warranty. And even at 5% or less, there must be "cosolvents" and corrosion preventers in this fuel to help avoid these problems. Gasolines for Cleaner Air Your use of gasoline with deposit control additives will help prevent deposits from formingin your engine and fuel system. That helps keep your engine intune and your emission control system working properly. It's good for your vehicle, you'll be and doing yourpart for cleaner air. Many gasolinesare now blendedwith oxygenates. General Motors recommends that you use gasolines with these blending materials, such as MTBE and ethanol. By doing so, you can help clean the air, especially in those parts of the country that have high carbon monoxide levels. 172