
Black plate (35,1)Cadillac STS Owner Manual - 2011
Trailer Brakes
Does the trailer have its own brakes? Be sure to
read and follow the instructions for the trailer brakes so
they are installed, adjusted and maintained properly.
Because the vehicle has StabiliTrak
®, do not try to tap
into the vehicle's hydraulic brake system. If you do, both
brake systems will not work well, or at all.
Trailer Wiring Harness
All of the electrical circuits required for the trailer lighting
system can be accessed at the driver side rear lamp
connector. This connector is located under the carpet
on the rear corner of the trunk compartment.
Driving with a Trailer
Towing a trailer requires a certain amount of
experience. Get to know the rig before setting out
for the open road. Get acquainted with the feel of
handling and braking with the added weight of the
trailer. And always keep in mind that the vehicle you
are driving is now longer and not as responsive as the
vehicle is by itself. Before starting, check all trailer hitch parts and
attachments, safety chains, electrical connectors,
lamps, tires and mirror adjustments. If the trailer has
electric brakes, start the vehicle and trailer moving and
then apply the trailer brake controller by hand to be sure
the brakes are working. This checks the electrical
connection at the same time.
During the trip, check occasionally to be sure that the
load is secure, and that the lamps and any trailer
brakes are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as
you would when driving the vehicle without a trailer.
This can help to avoid situations that require heavy
braking and sudden turns.
Passing
More passing distance is needed when towing a trailer.
Because the rig is longer, it is necessary to go much
farther beyond the passed vehicle before returning to
the lane.
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Black plate (37,1)Cadillac STS Owner Manual - 2011
Driving On Grades
Reduce speed and shift to a lower gearbeforestarting
down a long or steep downgrade. If the transmission is
not shifted down, the brakes might have to be used so
much that they would get hot and no longer work well.
On a long uphill grade, shift down and reduce the
vehicle's speed to around 45 mph (70 km/h) to reduce
the possibility of the engine and the transmission
overheating.
Vehicles can tow in D (Drive). Shift the transmission to
a lower gear if the transmission shifts too often under
heavy loads and/or hilly conditions.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a
lower temperature than at normal altitudes. If the engine
is turned off immediately after towing at high altitude on
steep uphill grades, the vehicle may show signs similar
to engine overheating. To avoid this, let the engine run
while parked, preferably on level ground, with the
automatic transmission in P (Park) for a few minutes
before turning the engine off. If the overheat warning
comes on, see Engine Overheating on page 6‑30.
Parking on Hills
{WARNING:
Parking the vehicle on a hill with the trailer
attached can be dangerous. If something goes
wrong, the rig could start to move. People can be
injured, and both the vehicle and the trailer can be
damaged. When possible, always park the rig on
a flat surface.
If parking the rig on a hill: 1. Press the brake pedal, but do not shift into P (Park) yet. Turn the wheels into the curb if facing downhill
or into traffic if facing uphill.
2. Have someone place chocks under the trailer wheels.
3. When the wheel chocks are in place, release the regular brakes until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking brake and shift into P (Park).
5. Release the brake pedal.
5-37

Black plate (1,1)Cadillac STS Owner Manual - 2011
Section 6 Service and Appearance Care
Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Accessories and Modifications . . . . . . . . . . . . . . . . . . 6-4
California Proposition 65 Warning . . . . . . . . . . . . . . . 6-5
California Perchlorate Materials Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Doing Your Own Service Work . . . . . . . . . . . . . . . . . . 6-5
Adding Equipment to the Outside of the Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
Gasoline Octane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
Gasoline Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
California Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Fuels in Foreign Countries . . . . . . . . . . . . . . . . . . . . . . 6-8
Filling the Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9
Filling a Portable Fuel Container . . . . . . . . . . . . . . . 6-11
Checking Things Under the Hood . . . . . . . . . . . . . . .6-12
Hood Release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12
Engine Compartment Overview . . . . . . . . . . . . . . . . 6-13
Engine Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16
Engine Oil Life System . . . . . . . . . . . . . . . . . . . . . . . . 6-20
Engine Air Cleaner/Filter . . . . . . . . . . . . . . . . . . . . . . . 6-21
Automatic Transmission Fluid . . . . . . . . . . . . . . . . . . 6-23
Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24
Engine Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25
Engine Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-30 Overheated Engine Protection
Operating Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32
Power Steering Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33
Windshield Washer Fluid . . . . . . . . . . . . . . . . . . . . . . 6-34
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-35
Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-38
Jump Starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-38
All-Wheel Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-43
Rear Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-44
Front Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-45
Headlamp Aiming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-46
Bulb Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-47
High Intensity Discharge (HID) Lighting . . . . . . . . 6-47
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-47
Back-Up Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-48
Replacement Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-48
Windshield Replacement . . . . . . . . . . . . . . . . . . . . . . . . .6-48
Windshield Wiper Blade Replacement . . . . . . . . . . .6-49
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-50
Winter Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-51
Tire Sidewall Labeling . . . . . . . . . . . . . . . . . . . . . . . . . 6-52
Tire Terminology and Definitions . . . . . . . . . . . . . . . 6-55
Inflation - Tire Pressure . . . . . . . . . . . . . . . . . . . . . . . . 6-58
High-Speed Operation . . . . . . . . . . . . . . . . . . . . . . . . . 6-60
6-1

Black plate (4,1)Cadillac STS Owner Manual - 2011
Service
For service and parts needs, visit your dealer. You
will receive genuine GM parts and GM-trained and
supported service people.
Genuine GM parts have one of these marks:
Accessories and Modifications
When non‐dealer accessories are added to the vehicle,
they can affect vehicle performance and safety,
including such things as airbags, braking, stability, ride
and handling, emissions systems, aerodynamics,
durability, and electronic systems like antilock brakes,
traction control, and stability control. Some of these
accessories could even cause malfunction or damage
not covered by the vehicle warranty.
Damage to vehicle components resulting from the
installation or use of non‐GM certified parts, including
control module modifications, is not covered under the
terms of the vehicle warranty and may affect remaining
warranty coverage for affected parts.
GM Accessories are designed to complement and
function with other systems on the vehicle. Your GM
dealer can accessorize the vehicle using genuine GM
Accessories. When you go to your GM dealer and ask
for GM Accessories, you will know that GM-trained and
supported service technicians will perform the work
using genuine GM Accessories.
Also, seeAdding Equipment to Your Airbag-Equipped
Vehicle on page 2‑71.
6-4

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.
6-15

Black plate (35,1)Cadillac STS Owner Manual - 2011
Brakes
Brake Fluid
The brake master cylinder
reservoir is filled with DOT
3 brake fluid. SeeEngine
Compartment Overview
on page 6‑13for
reservoir location and
access.
There are only two reasons why the brake fluid level in
the reservoir might go down:
.The brake fluid level goes down because of
normal brake lining wear. When new linings are
installed, the fluid level goes back up.
.A fluid leak in the brake hydraulic system can also
cause a low fluid level. Have the brake hydraulic
system fixed, since a leak means that sooner or
later the brakes will not work well. Do not top off the brake fluid. Adding fluid does not
correct a leak. If fluid is added when the linings are
worn, there will be too much fluid when new brake
linings are installed. Add or remove brake fluid, as
necessary, only when work is done on the brake
hydraulic system.
{WARNING:
If too much brake fluid is added, it can spill on the
engine and burn, if the engine is hot enough. You
or others could be burned, and the vehicle could
be damaged. Add brake fluid only when work is
done on the brake hydraulic system.
If the ignition is on and the brake fluid is low, the
CHECK BRAKE FLUID message displays in the Driver
Information Center (DIC). See DIC Warnings and
Messages on page 4‑76.
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Black plate (36,1)Cadillac STS Owner Manual - 2011
What to Add
DOT 3 brake fluid is recommended. DOT 4 brake fluid
is also compatible with the vehicle's brake system parts.
However, if DOT 4 fluid is used, it is recommended that
the brake hydraulic system be flushed and refilled with
new DOT 4 fluid at a regular maintenance service every
two years. SeeScheduled Maintenance
on page 7‑3.
Use new brake fluid from a sealed container only. See
Recommended Fluids and Lubricants on page 7‑9.
Always clean the brake fluid reservoir cap and the area
around the cap before removing it. This helps keep dirt
from entering the reservoir.
{WARNING:
With the wrong kind of fluid in the brake hydraulic
system, the brakes might not work well. This could
cause a crash. Always use the proper brake fluid. Notice:
.Using the wrong fluid can badly damage
brake hydraulic system parts. For example,
just a few drops of mineral-based oil, such
as engine oil, in the brake hydraulic system
can damage brake hydraulic system parts so
badly that they will have to be replaced. Do
not let someone put in the wrong kind of
fluid.
.If brake fluid is spilled on the vehicle's
painted surfaces, the paint finish can be
damaged. Be careful not to spill brake fluid
on the vehicle. If you do, wash it off
immediately. See
Washing Your Vehicle
on
page 6‑109
.
Brake Wear
This vehicle has disc brakes. Disc brake pads have
built-in wear indicators that make a high-pitched
warning sound when the brake pads are worn and new
pads are needed. The sound can come and go or be
heard all the time the vehicle is moving, except when
applying the brake pedal firmly.
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Black plate (37,1)Cadillac STS Owner Manual - 2011
{WARNING:
The brake wear warning sound means that soon
the brakes will not work well. That could lead to a
crash. When the brake wear warning sound is
heard, have the vehicle serviced.
Notice: Continuing to drive with worn-out brake
pads could result in costly brake repair.
Some driving conditions or climates can cause a brake
squeal when the brakes are first applied or lightly
applied. This does not mean something is wrong with
the brakes.
Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated, inspect
brake pads for wear and evenly tighten wheel nuts in
the proper sequence to torque specifications in
Capacities and Specifications on page 6‑128.
Brake linings should always be replaced as complete
axle sets.
Brake Pedal Travel
See your dealer if the brake pedal does not return to
normal height, or if there is a rapid increase in pedal
travel. This could be a sign that brake service might be
required.
Brake Adjustment
Every time the brakes are applied, with or without the
vehicle moving, the brakes adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together if
the vehicle is to have really good braking. The vehicle
was designed and tested with top-quality brake parts.
When parts of the braking system are replaced —for
example, when the brake linings wear down and new
ones are installed —be sure to get new approved
replacement parts. If this is not done, the brakes might
not work properly. For example, if someone puts in
brake linings that are wrong for the vehicle, the balance
between the front and rear brakes can change —for the
worse. The braking performance expected can change
in many other ways if the wrong replacement brake
parts are installed.
6-37