1998 Buick Riviera Owner's Manual

How to Add Coolant to the Radiator1. You can remove theradiator pressure capwhen the coolingsystem, including theradiator pressure cap andupper radiator hose, isno longer hot. Turn thepressure cap slowlycounterclockwise until itIfirst stops. (Don’t pressdown while turning thepressure cap.)If you hear a hiss, wait for that to stop. A hiss meansthere is still some pressure left.2. Then keep turning thepressure cap, hut nowpush down as youturn it. Remove thepressure cap.3. Fill the radiator with theproper DEX-COOL@coolant mixture, up tothe base of the fillerneck. (See “EngineCoolant” in the Indexfor more informationabout the propercoolant mixture.)