1997 Pontiac Sunfire Owner's Manual - Page 226

How to Add Coolant to the Coolant Surge Tank If you haven't found a problem yet, but the coolant level isn't at the FULL COLD mark, add a 50/50 mixture of clean water (preferably distilled) and DEX-COOL@ coolant at the coolant surge tank, but be sure the cooling system, including the coolant surge tank pressure cap, is you cool b'efore do it. (See "Engine Coolant" in the Index for more information.) Steam and scalding liquids from a hot cooling system canblow out andburn you badly. They are under pressure, if you turn the coolant and surge tank pressure cap even a little they can come out at high speed. Never turn the cap when the cooling system, including the coolant surge tank pressure cap, is hot. Wait for the cooling system andcoolant surge tank pressure cap to cool if you ever have turn to the pressure cap. -- -- 5-18