Cadillac 2007 DTS Owner's Manual page 376

4.6L L37 Engine shown, 4.6L LD8 Engine similar
376
3. Fill the coolant
surge tank with the
proper mixture
to the FULL COLD
mark on the
side of the coolant
surge tank.
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. Then replace the cap. Be sure the cap is
hand-tight and fully seated.