2009 Cadillac DTS Owner's Manual - Page 331

Notice: If the pressure cap is not tightly installed, coolant loss and possible engine damage may occur. Be sure the cap is properly and tightly secured. If coolant is needed, add the proper DEX-COOL® coolant mixture at the coolant recovery tank. Coolant Surge Tank Pressure Cap Notice: If the pressure cap is not tightly installed, coolant loss and possible engine damage may occur. Be sure the cap is properly and tightly secured. 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. 5-27 The coolant surge tank pressure cap must be fully installed on the coolant surge tank. See Engine Compartment Overview on page 5-12 for more information on location.