2011 Cadillac DTS Owner's Manual - Page 330

Turn the pressure cap slowly counterclockwise. If you hear a hiss, wait for that to stop. A hiss means there is still some pressure left. 2. Keep turning the cap and remove it. 3. Fill the coolant surge tank with the proper mixture to the FULL COLD mark on the side of the coolant surge tank. 4.6L L37 Engine shown, 4.6L LD8 Engine similar 4. With the coolant surge tank 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 the FULL COLD mark on the side of the coolant surge tank. 5. Replace the cap. Be sure the cap is hand‐tight and fully seated. 6-28