1996 Pontiac Sunfire Owner's Manual - Page 206

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 TM antifreeze at the coolant surge tank, but be sure the cooling system, including the coolant surge tank pressure cap, is cool before you do it. (See"Engine Coolant" in the Index for more .information.) A CAUTION: Steam and scalding liquids from a hot cooling system can blow out and burn you badly. They are under pressure,and if you turn thecoolant 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 cap and coolant surge tank pressure to cool if you ever have to turn the pressure cap. -- --