Cadillac 2006 CTS Owner's Manual page 309

3. Fill the coolant surge tank with the proper mixture,
to slightly above the FULL COLD/FROID line on
the side of the coolant surge tank.
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. The upper
radiator hose is the top hose coming out of
the radiator, on the passenger's side of the
vehicle. 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 FULL COLD/FROID
line on the side of the coolant surge tank.
5. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
Start the engine and allow it to warm up. If the
Check Coolant Level message does not appear on
the Driver Information Center (DIC), the coolant is at
the proper fill level. If a Check Coolant Level message
does appear, repeat Steps 1 to 3 then reinstall the
pressure cap, or see your dealer.
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