1995 Cadillac Seville Owner's Manual - Page 274

FUEL Use premium unleadedgasoline rated at 91 octane or higher. It should and meet specifications ASTM D4814 in the United States CGSB 3.5-92 in Canada. Thesefuels should have the properadditives, so you should not have to add anything to the fuel. In the United States Canada, it's easy to be sure get the right and you kind of gasoline (unleaded). You'll see UNLEADEDright on the pump. And only unleaded nozzles will fit into your vehicle's filler neck. - is Be sure the posted octane at least 91. If the octaneis lessthan 91, you may get a heavy knocking noise when you drive.(In an emergency, you may be able to use lower octane -- as low as 87 -- if heavy knocking does not occur.) If you're using91 orhigher octane unleaded gas and you still get heavy knocking, your engine needsservice. What aboutgasoline with blending materials that contain oxygen (oxygenates), such as MTBE or alcohol? MTBE is "methyl tertiary-butyl ether." Fuel that no more than is 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 foryour vehicle. Methanol is methyl or wood alcohol. I NOTICE: Fuel that is more than 5% methanol is bad for your vehicle. Don't use it. It can corrode metal partsin your fuel system and also damage plastic and rubber parts. That damage wouldn't be covered under your warranty. And even 5% or less, there must at be "cosolvents" and corrosion preventers this fuel to help in avoid these problems. 6-3