Cadillac XLR-V 2006 Owner's Manual page 340

Checking Coolant
The engine coolant surge tank is located toward the
rear of the engine compartment on the driver's side
of the vehicle. For more information on location,
see Engine Compartment Overview on page 6-12.
6-24
CAUTION:
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Turning the surge tank pressure cap when the
engine and radiator are hot can allow steam
and scalding liquids to blow out and burn you
badly. Never turn the surge tank pressure
cap — even a little — when the engine and
radiator are hot.
The vehicle must be on a level surface. When your
engine is cold, the coolant level should be at the
FULL COLD mark, located on the side of the surge
tank that faces the front.
If the LOW COOLANT message on the Driver
Information Center (DIC) comes on and stays on,
it means you are low on engine coolant. See
DIC Warnings and Messages on page 3-67 for
more information.