1993 GMC Jimmy Owner's Manual - Page 270

Senrice & Appearance,Cam NOTICE . . . . L KO661 The8thdigit of yourVehicleIdentificationNumber(VIN)showsthecode of yourinstrument letter for your engine. You will find the VIN at the top left panel,(See"VehicleIdentificationNumber"intheIndex.) or higher.Withthe 4.3L Useregularunleadedgasolineratedat87octane (Code W) engine,usepremiumunleadedgasolineratedat 91 octane or higher for high power performance, when towing a trailer or with a high payloadrequirement.Butwhenoperatingwithalightloadasanormal or regularunleadedgasolines. condition,youmayusemiddlegrade D4814 inthe US. ThegasolineyouuseshouldmeetspecificationsASTM andCGSB 3.5-92in Canada.Thesefuelsshouldhavetheproperadditives, so you should not have to add anything to the fuel. In the US. andCanada,it'seasyto be sure you get the right kind of gasoline(unleaded).You'llsee UNLEADED rightonthepump.Andonly unleaded nozzles will fit into your vehicle's filler neck. 91 forpremium, 89 formiddtegrade Besurethepostedoctaneisatleast and 87 forregular. If theoctaneislessthan 87, youmay get aheavy knockingnoisewhenyoudrive. If it'sbadenough, it candamageyour engine. 6-4