2009 Cadillac STS-V Owner's Manual - Page 355

Checking Coolant The vehicle must be on a level surface when checking the coolant level. Check to see if coolant is visible in the coolant surge tank. If the coolant inside the coolant surge tank is boiling, do not do anything else until it cools down. If coolant is visible but the coolant level is not at or above the FULL COLD/FROID line, add a 50/50 mixture of clean, drinkable water and DEX-COOL® coolant at the coolant surge tank, but be sure the cooling system is cool before this is done. When the engine is cold, the coolant level should be at or above the FULL COLD/FROID line on the side of the coolant surge tank. Follow the arrow from the top of the tank down the side to the horizontal mark. If it is not, there could be a leak in the cooling system. If the coolant is low, add the coolant or take the vehicle to a dealer/retailer for service. The coolant surge tank and pressure cap are located on the driver's side of the vehicle, toward the rear of the engine compartment. See Engine Compartment Overview on page 5-12 for more information on location. 5-29