1994 Pontiac Grand Am Owner's Manual - Page 173

Service & Appearance Care Fuel 2.3L High Output Quad 4 Engine (Code A): The 8th digit of your Vehicle Identification Number (VIN) shows the code letter for your engine. You will find the VIN at the top left of your instrument panel. (See "Vehicle Identification Number" in the Index.) Use premium unleaded gasoline rated at 91 octane or higher. You may use middle grade or regular unleaded gasolines, but your vehicle may not accelerate as well. The gasoline you use should meet specifications ASTM D4814in the U.S. 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 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 the posted octane for premium is at least 91 (at least 89 for middle grade and 87 for regular). 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. 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 system and alsodamage plastic and rubber parts. That damage wouldn't be covered under your warranty. And even at5% or less, there must be "cosolvents" and corrosion preventers in this fuel to help avoid these problems. 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 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? .. 172