1995 Pontiac Bonneville Owner's Manual - Page 216

Fuel 3800 Engine (Code K) The 8th digit of your vehicle identification number (VIN) shows the code letter for your engine. You will find the VIN at the left of your instrument top panel. (See "Vehicle Identification Number" in the Index.) Use regular unleaded gasoline rated at 87 octane or higher. It should meet specifications ASTM D48 14 in the United States andCGSB 3.5-92 in Canada. These fuels should have theproper additives, so you should not have to add anythingto the fuel. In the UnitedStates 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 postedoctane is at least87. 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. If you're using fuel rated at 87 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'thave 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 withblending 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 finefor 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 than methanol is bad for 5% 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 at or 5% less, there must be "cosolvents" and corrosion preventers in this fuel help avoid these to problems.