1995 Buick Riviera Owner's Manual - Page 212

Fuel 3800 L36 (Code K) Engine The 8thdigit 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 regular unleaded gasoline rated at 87 octane or higher. It should meet specifications ASTM D4814 in the United States 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 United States 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 intoyour vehicle's filler neck. Be sure the posted octane is atleast 87. 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. 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 for your vehicle. Ethanol is ethyl or grain alcohol. Properly-blended fuel that is nomore than 10%ethanol is fine foryour vehicle. Methanol is methyl or wood alcohol. I NOTICE: If you're using fuel rated at octane or higher and you 87 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 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 plast and rubber parts. That damage wouldn't be covered under your warranty. And even 5% or at less, there must be "cosolvents" and corrosion preventers in this fuel to help avoid these problems. 6-3