Cadillac 1998 Eldorado Owner's Manual page 263

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 about 2.5 inches (6.4 cm)
below the base of the filler neck.
a
5. Then replace the pressure cap. Be sure the arrows on
the pressure cap line up like this.
Start the engine and allow it to warm up. If the CHECK
COOLANT LEVEL message does not appear on the
Driver Information Center, coolant is at the proper fill
level. If a CHECK COOLANT LEVEL message does
appear, repeat Steps 1 through 3 or see your dealer.
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