1995 GMC Jimmy Owner's Manual - Page 243

The gasoline you use should meetspecifications ASTM D4814 in the United States and CGSB 3.5-92 in Canada. These fuels should have the anything to the fuel. proper additives, so you should not have to add In the United States and Canada, it's easy to besure 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 is at least 91 for premium, 89 formiddle 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. If you're using fuel rated at 91 octane or higher and youstill hear heavy knocking, your engine needs service. But don't worryif you heara little pinging noise when you're accelerating or driving up a hill.That's normal, and you don't have to buya higher octane fuel to get rid of it. It's the heavv. 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 foryour 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 thatis more than 5% methanol is bad for your vehicle. Don't useit. 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 even5% or less, there at must be "cosolvents" and corrosion preventers in this fuel to help avoid these problems. 6-3