1999 GMC Sierra 1500 Pickup Owner's Manual - Page 321

1 CAUTION 4 Addingonly plain water to yourcoolingsystemcanbedangerous. Plain water,orsome otherliquidlikealcohol,canboilbeforeth( )percoolantmixwill. Your vehicle'scoolantwarningsystemisset forthepropercoolantmix.Withplainwaterorthewrongmix,your engine could gettoohotbutyouwouldn'tgettheoverheatwarning. Your engine could catch fire andyouorotherscouldbeburned.Use a 50/50 mixof clean waterandaproperantifreeze. NOTICE If you use an improper coolant mix, your engine could overheat and 1: badly damaged. The repair cost wouldn't be covered by yourwarranty. 1 much water in the can mix freeze and x k +?e t line radiator, heater core and other parts. Someconditions,suchasairtrapped in thecoolingsystem,canaffectthe coolantlevelintheradiator.Checkthecoolantlevel when theengineiscold and follow the steps under "Adding Coolant" for the proper waytoadd coolant. If youhave the lowcoolantwarningsystem,refertotheGeneralMotors fill procedure. (To Service Manual orseeyourdealerforthepropercoolant purchaseaServiceManual,see"ServicePublications'' in theIndex.)Using thewrong fill procedurecancausealowcoolantwarningindication. If youhave to addcoolantmorethanfourtimesayear,haveyourdealer check your cooling system. NOTICE If you use the proper coolant, you don'thave to add extra inhibitors or additives which claim to improve the system.Thesecanbeharmful. .I - 6-43