2003 Cadillac DeVille Owner's Manual - Page 306

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. 5. Then replace the pressure cap. Be sure the arrow on the pressure cap lines up like this. 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 4.5 inches (1 1.4 cm) from the top of the filler neck. 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 to 3 and reinstall the pressure cap or see your dealer. 5-35