1996 GMC Jimmy Owner's Manual - Page 250

Fuel ~- II your vehicle is certified to meet Califol [aEmission Standards (indicated on the underhood tu1 -up label), it is designed to operateon fuels that meet ( lifornia specifications. If such fuels are not availa e in states adopting California emissions standards, mr vehicle will operate satisfactorily on fuels meetin federal specifications, but emission control syste~ performance may be afXected.The malfunction indicatl lamp on your instrument panel may turn on and/or our vehicle may fail asmog-check test. If this occurs eturn to your authorized GM dealer fordiagnosis to der mine the cause of failure. In the event it is determil d that the cause of the condition is the type of fuels ;ed, repairs may not be covered by your warranty. In Canada, some gasolines contain an oct; additive called MMT. If you see such fuel emission control system performance ma; and the malfunction indicator lampon yo panel may turn on. If this happens, return authorized GM dealer for service. Use regular unleaded gasoline rated at 87 octane or higher. At a minimum, it should meet specifications ASTM D4814 in the United States and CGSB 3.5-M93 in Canada. Improved gasoline specifications have been developed by the American Automobile Manufacturers Association (AAMA) for bettervehicle performance and engine protection.G'asolines meeting the AAMA specification could provide improved driveability and emission controlsystem protection compared to other gasolines. Be sure the posted octane is at least 87. the octane is If 'lessthan 87, you may get a heavy knocking noise when you drive. If it's bad enough,. it candamage your engine. If you're using fuel rated at 87 octane orhigher and you still hear heavy knocking, your engine needs service. But don't worry if you hear a littie pinging noise when you're accelerating ordriving up a hill. That's normal, and you don't have tobuy a higher octane fuelto get rid of pinging. It's the heavy, constant knock that means you have a problem. e enhancing your leteriorate instrument your 6-3