Oldsmobile AURORA 2001 Owner's Manual page 242

1. You can remove the coolant surge tank pressure
cap when the cooling system, including the coolant
surge tank pressure cap and upper radiator hose,
is no longer hot. Turn the pressure cap slowly
counterclockwise (left) about one
then stop.
If you hear a hiss, wait for that to stop. A hiss means
there is still some pressure left.
5-16
-
quarter turn and
2. Then keep turning the
pressure cap slowly,
and remove it.
3. Then fill the coolant
surge tank with the
proper mixture, to the
base of the filler neck.