Page 363 of 528
Black plate (13,1)Cadillac STS Owner Manual - 2011
2. Then go to the front of the vehicle and find thesecondary hood release lever. The lever is located
under the front edge of the grille near the center.
Push the release lever up and raise the hood.
Before closing the hood, be sure all the filler caps are
on properly. Then pull the hood down and close it firmly.
Engine Compartment Overview
Your vehicle may be equipped with front compartment
underhood sight shields, which surround the vehicle's
engine cover. These sight shields will need to be
removed in order to access some of the underhood
components in your vehicle.
To remove the sight shields, turn the fasteners on each
shield to the left until they pop out. Then remove the
fasteners and lift the shields up and away from the
tower to tower brace.
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Black plate (15,1)Cadillac STS Owner Manual - 2011
After you have removed the sight shields (if equipped):A. Underhood Fuse Block. See Underhood Fuse
Block on page 6‑116.
B. Remote Negative (-) Terminal. See Jump Starting
on page 6‑38.
C. Remote Positive (+) Terminal. See Jump Starting
on page 6‑38.
D. Battery. See Battery on page 6‑38.
E. Passenger Compartment Air Filter. See Passenger
Compartment Air Filter on page 4‑50.
F. Power Steering Fluid Reservoir. See Power
Steering Fluid on page 6‑33.
G. Engine Oil Fill Cap. See “When to Add Engine Oil”
under Engine Oil on page 6‑16.
H. Engine Oil Dipstick (Out of View). See “Checking
Engine Oil” underEngine Oil on page 6‑16. I. Brake Master Cylinder Reservoir. See
“Brake
Fluid” under Brakes on page 6‑35.
J. Engine Coolant Surge Tank and Pressure Cap. See Cooling System on page 6‑24.
K. Engine Air Cleaner/Filter. See Engine Air Cleaner/
Filter on page 6‑21.
L. Windshield Washer Fluid Reservoir. See “Adding
Washer Fluid” underWindshield Washer Fluid
on
page 6‑34.
If your vehicle is equipped with front compartment
underhood sight shields, before closing the hood be
sure to reinstall the sight shields. To reinstall the
shields, locate the tabs on the left and right sides and
insert them into the openings in the tower to tower
brace. Then insert the fasteners into the top of the
shield and push the fasteners back into place.
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Page 366 of 528

Black plate (16,1)Cadillac STS Owner Manual - 2011
Engine Oil
To ensure proper engine performance and long life,
careful attention must be paid to engine oil. Following
these simple, but important steps will help protect your
investment:
.Always use engine oil approved to the proper
specification and of the proper viscosity grade. See
“Selecting the Right Engine Oil.”
.Check the engine oil level regularly and maintain
the proper oil level. See“Checking Engine Oil”and
“When to Add Engine Oil.”
.Change the engine oil at the appropriate time. See
Engine Oil Life System on page 6‑20.
.Always dispose of engine oil properly. See “What
to Do With Used Oil.”
Checking Engine Oil
It is a good idea to check the engine oil level at each
fuel fill. In order to get an accurate reading, the vehicle
must be on level ground. The engine oil dipstick handle
is a yellow loop. See Engine Compartment Overview
on
page 6‑13for the location of the engine oil dipstick.
Obtaining an accurate oil level reading is essential: 1. If the engine has been running recently, turn off the engine and allow several minutes for the oil to
drain back into the oil pan. Checking your oil level
too soon after engine shut off will not provide an
accurate oil level reading.
2. Pull out the dipstick and clean it with a paper towel or cloth, then push it back in all the way. Remove it
again, keeping the tip down, and check the level.
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Black plate (22,1)Cadillac STS Owner Manual - 2011
When to Inspect the Engine Air
Cleaner/Filter
Inspect the air cleaner/filter at the scheduled
maintenance intervals and replace it at the first oil
change after each 80 000 km (50,000 mile) interval. See
Scheduled Maintenance
on page 7‑3for more
information. If you are driving in dusty/dirty conditions,
inspect the filter at each engine oil change.
How to Inspect the Engine Air
Cleaner/Filter
To inspect the air cleaner/filter remove the filter from the
vehicle and lightly shake the filter to release loose dust
and dirt. If the filter remains caked with dirt, a new filter
is required.
To inspect or replace the filter:
1. Remove the two screws located on the top of the cover.
2. Disconnect the coolant recovery hose so that it is not going across the top of the engine air cleaner/
filter.
3. Loosen the clamp and remove the duct from the passenger's side of the engine air cleaner/filter. 4. The two sides of the airbox are hinged at the
bottom. Open the airbox by pushing the top of the
airbox cover toward the engine.
5. Remove the air filter by lifting it straight up through the opening in the airbox.
6. Inspect or replace the engine air cleaner/filter. See Maintenance Replacement Parts
on page 7‑11for
the correct part number for the filter.
7. Reinstall the cover by reversing Steps 1 through 4.
{WARNING:
Operating the engine with the air cleaner/filter off
can cause you or others to be burned. The air
cleaner not only cleans the air; it helps to stop
flames if the engine backfires. Use caution when
working on the engine and do not drive with the
air cleaner/filter off.
Notice: If the air cleaner/filter is off, dirt can easily
get into the engine, which could damage it. Always
have the air cleaner/filter in place when you are
driving.
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Black plate (27,1)Cadillac STS Owner Manual - 2011
Checking Coolant
The vehicle must be on a level surface when checking
the coolant level.
The coolant surge tank and pressure cap are located on
the driver's side of the vehicle, toward the rear of the
engine compartment. SeeEngine Compartment
Overview
on page 6‑13for more information on
location. 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 for service
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Page 381 of 528

Black plate (31,1)Cadillac STS Owner Manual - 2011
If Steam Is Coming From The Engine
Compartment
{WARNING:
Steam from an overheated engine can burn you
badly, even if you just open the hood. Stay away
from the engine if you see or hear steam coming
from it. Turn it off and get everyone away from the
vehicle until it cools down. Wait until there is no
sign of steam or coolant before you open
the hood.
If you keep driving when the vehicles engine is
overheated, the liquids in it can catch fire. You or
others could be badly burned. Stop the engine if it
overheats, and get out of the vehicle until the
engine is cool.
SeeOverheated Engine Protection Operating
Mode
on page 6‑32for information on driving to
a safe place in an emergency.
If No Steam Is Coming From The
Engine Compartment
An overheat warning, can indicate a serious problem.
If an engine overheat warning is displayed but no steam
can be seen or heard, the problem may not be too
serious. Sometimes the engine can get a little too hot
when the vehicle:
.Climbs a long hill on a hot day.
.Stops after high-speed driving.
.Idles for long periods in traffic.
.Tows a trailer.
If the overheat warning is displayed with no sign of
steam: 1. Turn the air off.
2. Turn the heater on to the highest temperature and to the highest fan speed. Open the windows as
necessary.
3. In heavy traffic, let the engine idle in N (Neutral) while stopped. If it is safe to do so, pull off the
road, shift to P (Park) or N (Neutral) and let the
engine idle.
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Black plate (32,1)Cadillac STS Owner Manual - 2011
If the engine coolant temperature gauge is no longer in
the overheat zone or an overheat warning no longer
displays, the vehicle can be driven. Continue to drive
the vehicle slow for about 10 minutes. Keep a safe
vehicle distance from the car in front of you. If the
warning does not come back on, continue to drive
normally.
If the warning continues, pull over, stop, and park the
vehicle right away.
If there is no sign of steam, idle the engine for
three minutes while parked. If the warning is still
displayed, turn off the engine until it cools down. Also,
see "Overheated Engine Protection Operating Mode"
later in this section.Overheated Engine Protection
Operating Mode
This operating mode allows your vehicle to be driven to
a safe place in an emergency. Should an overheated
engine condition exist, an overheat protection mode
which alternates firing groups of cylinders helps prevent
engine damage. In this mode, you will notice a loss in
power and engine performance. An engine overheat
warning will indicate that an overheat condition exists.
Driving extended miles (km) and/or towing a trailer in
the overheat protection mode should be avoided.
Notice:After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any
repair. The engine oil will be severely degraded.
Repair the cause of coolant loss and change the oil.
See Engine Oil on page 6‑16.
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Page 390 of 528
Black plate (40,1)Cadillac STS Owner Manual - 2011
Your vehicle has a remote negative (−) ground
location, as shown in the illustration. It is located
on the passenger side front shock tower. See
Engine Compartment Overview
on page 6‑13.
You should always use this remote ground
location, instead of the terminal on the battery. Notice:
If you connect a negative cable to the
Engine Control Module (ECM), ECM mounting
bracket, or any cables that attach to the ECM
bracket, you may damage the ECM. Always attach
the negative cable to your vehicle's remote negative
ground location, instead of the ECM, ECM bracket,
or any cables attached to the ECM bracket.
{WARNING:
An electric fan can start up even when the engine
is not running and can injure you. Keep hands,
clothing and tools away from any underhood
electric fan.
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