Oldsmobile 2001 Aurora - Manual (Page 243)

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4. With the coolant surge tank pressure cap off, start
the engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the engine
cooling fans.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches the base of the filler neck.
5. Then replace the pressure cap. Be sure the arrows on
the pressure cap line up like this.