Oldsmobile 1999 Aurora - Manual (Page 225)

yellow blue
5-17
3. Then fill the coolant surge tank with the proper
mixture, to FULL COLD.
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 FULL COLD.