1993 GMC Yukon Owner's Manual - Page 270
1993 GMC Yukon Manual
Page 270 highlights
Maint@nanceSchedule Section 7 of thismanual,"ScheduledMaintenanceServices",explainsthe maintenanceyournewvehicleneeds,andwhen it shouldbedone. It also your hasaformthatyoucanuse to recordthemaintenanceworkdoneon vehicle.Besure to read thisinformation. Use regularunleadedgasolinerated at 87 octaneorhigher. It should meet specifications ASTM 04814 in the US. and CGSB 3.5-92in Canada.These so youshouldnothave to add fuelsshouldhavetheproperadditives, anything to the fuel. Inthe US. andCanada, it's easy to besureyougettheright kind of gasoline(unleaded). You'llsee UNLEADED right on thepump.Andonly unleadednozzles will fit intoyourvehicle'sfillerneck. . Besurethepostedoctane is atleast 87. If theoctane is lessthan 87, you If it'sbadenough, it can maygetaheavyknockingnoisewhenyoudrive. damage your engine.