2004 BUICK CENTURY Service engine soon

Notice:Use only engine oil identied as meeting
GM Standard GM6094M and showing the American
Petroleum Institute Certied For Gasoline Engines
starburst symbol. Failure to use the recommended
oil can result in engine damage not covered by
your warranty.
GM Goodwrench
®oil meets all the requirements for
your vehicle.
If you are in an area of extreme cold, where the
temperature falls below−20°F (−29°C), it is
recommended that you use either an
SAE 5W-30 synthetic oil or an SAE 0W-30 oil. Both will
provide easier cold starting and better protection for
your engine at extremely low temperatures.
Engine Oil Additives
Do not add anything to your oil. The recommended oils
with the starburst symbol that meet GM Standard
GM6094M are all you will need for good performance
and engine protection.
When to Change Engine Oil
(GM Oil Life System)
Your vehicle has a computer system that lets you know
when to change the engine oil and lter. This is
based on engine revolutions and engine temperature,
and not on mileage. Based on driving conditions,
the mileage at which an oil change will be indicated can
vary considerably. For the oil life system to work
properly, you must reset the system every time the oil is
changed.
When the system has calculated that oil life has been
diminished, it will indicate that an oil change is
necessary. A CHANGE OIL SOON light will come on.
Change your oil as soon as possible within the next
two times you stop for fuel. It is possible that, if you are
driving under the best conditions, the oil life system
may not indicate that an oil change is necessary for over
a year. However, your engine oil and lter must be
changed at least once a year and at this time the system
must be reset. Your dealer has GM-trained service
people who will perform this work using genuine GM
parts and reset the system. It is also important to check
your oil regularly and keep it at the proper level.
If the system is ever reset accidentally, you must change
your oil at 3,000 miles (5 000 km) since your last oil
change. Remember to reset the oil life system whenever
the oil is changed.
5-16

How to Reset the CHANGE OIL SOON
Light
The GM Oil Life System calculates when to change
your engine oil and lter based on vehicle use. Anytime
your oil is changed, reset the system so it can
calculate when the next oil change is required. If a
situation occurs where you change your oil prior to a
CHANGE OIL SOON light being turned on, reset
the system.
After changing the engine oil, reset the system by
performing the following steps:
1. With the engine off, turn the ignition key to RUN.
2. Fully press and release the accelerator pedal slowly
three times within ve seconds.
If the CHANGE OIL SOON light ashes, the system
is resetting.
3. Turn the key to OFF, then start the vehicle. The oil
life will change to 100 percent.
If the CHANGE OIL SOON light comes back on
when you start your vehicle, the engine oil life
system has not reset. Repeat the procedure.
What to Do with Used Oil
Used engine oil contains certain elements that may be
unhealthy for your skin and could even cause cancer.
Do not let used oil stay on your skin for very long. Clean
your skin and nails with soap and water, or a good
hand cleaner. Wash or properly dispose of clothing or
rags containing used engine oil. See the manufacturer’s
warnings about the use and disposal of oil products.
Used oil can be a threat to the environment. If you
change your own oil, be sure to drain all the oil from the
lter before disposal. Never dispose of oil by putting it
in the trash, pouring it on the ground, into sewers, or into
streams or bodies of water. Instead, recycle it by
taking it to a place that collects used oil. If you have a
problem properly disposing of your used oil, ask
your dealer, a service station or a local recycling center
for help.
5-17

When the engine is cold,
the coolant level should be
at or above the COLD
mark on the coolant
recovery tank. If it is not,
there may be a leak
at the pressure cap or in
the radiator hoses,
heater hoses, radiator,
water pump, or somewhere
else in the cooling
system.
{CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Do not touch them. If
you do, you can be burned.
Do not run the engine if there is a leak. If you
run the engine, it could lose all coolant. That
could cause an engine re, and you could be
burned. Get any leak xed before you drive the
vehicle.If there seems to be no leak, with the engine on, check
to see if the electric engine cooling fans are running.
If the engine is overheating, both fans should be
running. If they are not the vehicle needs service.
Notice:Engine damage from running your engine
without coolant is not covered by your warranty. See
“Overheated Engine Protection Operating Mode”
in the Index for information on driving to a safe
place in an emergency.
Notice:Using coolant other than DEX-COOL
®may
cause premature engine, heater core or radiator
corrosion. In addition, the engine coolant may
require changing sooner, at 30,000 miles (50 000 km)
or 24 months, whichever occurs rst. Any repairs
would not be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your vehicle.
5-29

Scheduled Maintenance
When the CHANGE OIL SOON light comes on, it
means that service is required for your vehicle. Have
your vehicle serviced as soon as possible within the
next 600 miles (1 000 km). It is possible that, if you
are driving under the best conditions, the engine oil
life system may not indicate that vehicle service
is necessary for over a year. However, your engine oil
and lter must be changed at least once a year and
at this time the system must be reset. Your GM
Goodwrench dealer has GM-trained service technicians
who will perform this work using genuine GM parts
and reset the system.
If the engine oil life system is ever reset accidentally,
you must service your vehicle within 3,000 miles
(5 000 km) since your last service. Remember to reset
the oil life system whenever the oil is changed. See
Engine Oil on page 5-13for information on the Engine
Oil Life System and resetting the system.When the CHANGE OIL SOON light appears,
certain services, checks and inspections are required.
Required services are described in the following for
“MaintenanceI” and “MaintenanceII.” Generally,
it is recommended that your rst service be
MaintenanceI, your second service be MaintenanceII
and that you alternate MaintenanceIand MaintenanceII
thereafter. However, in some cases, MaintenanceII
may be required more often.
MaintenanceI— Use MaintenanceIif the light comes
on within ten months since vehicle was purchased or
MaintenanceIIwas performed.
MaintenanceII— Use MaintenanceIIif the previous
service performed was MaintenanceI. Always use
MaintenanceIIwhenever the light comes on ten months
or more since the last service or if the light has not
come on at all for one year.
6-4

E
Electrical System
Add-On Equipment......................................5-97
Fuses and Circuit Breakers...........................5-97
Headlamp Wiring.........................................5-97
Power Windows and Other Power Options......5-97
Windshield Wiper Fuses...............................5-97
Emergency Trunk Release Handle.....................2-14
Emissions Inspection and Maintenance
Programs...................................................3-39
Engine
Air Cleaner/Filter.........................................5-18
Battery.......................................................5-41
Change Engine Oil Light...............................3-41
Check and Service Engine Soon Light............3-36
Coolant......................................................5-22
Coolant Heater............................................2-21
Coolant Temperature Gage...........................3-35
Coolant Temperature Warning Light................3-35
Drive Belt Routing.......................................6-14
Engine Compartment Overview......................5-12
Exhaust.....................................................2-29
Oil .............................................................5-13
Overheating................................................5-25
Starting......................................................2-20
Engine Cooling When Trailer Towing..................4-45
Engine Oil Additives........................................5-16Enhanced Traction System (ETS)........................ 4-9
Warning Light.............................................3-34
Entry Lighting.................................................3-15
Event Data Records (EDR)................................ 7-9
Express-Down Window....................................2-16
Extender, Safety Belt.......................................1-27
Exterior Lamps...............................................3-12
F
Filter
Engine Air Cleaner......................................5-18
Finding a Program Type (PTY) Station.......3-49, 3-56
Finding a Station....................................3-46, 3-53
Finish Care....................................................5-92
Finish Damage...............................................5-93
Fixed Mast Antenna........................................3-64
Flash-to-Pass................................................... 3-6
Flat Tire........................................................5-74
Flat Tire, Changing.........................................5-75
Fluid
Automatic Transaxle.....................................5-19
Power Steering...........................................5-35
Windshield Washer......................................5-36
FM ...............................................................3-63
Folding Rear Seat............................................ 1-5
Following Distance..........................................4-43
5

Restraint System Check (cont.)
Replacing Restraint System Parts After a
Crash.....................................................1-59
Restraint Systems
Checking....................................................1-58
Replacing Parts...........................................1-59
Resynchronization............................................. 2-9
Retained Accessory Power (RAP)......................2-20
Right Front Passenger Position, Safety Belts......1-20
Roadside
Assistance Program....................................... 7-5
Rocking Your Vehicle To Get It Out...................4-31
Routing, Engine Drive Belt...............................6-14
Running Your Engine While You Are Parked.......2-30
S
Safety Belt
Reminder Light............................................3-30
Safety Belts
Care of......................................................5-91
Center Passenger Position............................1-20
Driver Position............................................1-12
How to Wear Safety Belts Properly................1-11
Questions and Answers About Safety Belts.....1-10
Rear Safety Belt Comfort Guides for Children
and Small Adults......................................1-25
Rear Seat Passengers.................................1-22
Right Front Passenger Position......................1-20Safety Belts (cont.)
Safety Belt Extender....................................1-27
Safety Belt Use During Pregnancy.................1-19
Safety Belts Are for Everyone......................... 1-6
Safety Chains.................................................4-42
Safety Warnings and Symbols.............................. iii
Scheduled Maintenance..................................... 6-4
Seats
Head Restraints............................................ 1-5
Manual........................................................ 1-2
Reclining Seatbacks...................................... 1-3
Six-Way Power Seats.................................... 1-3
Split Folding Rear Seat.................................. 1-5
Securing a Child Restraint
Center Rear Seat Position............................1-44
Designed for the LATCH System...................1-42
Rear Outside Seat Position...........................1-42
Right Front Seat Position..............................1-47
Security Feedback............................................ 2-6
Security Light.................................................3-41
Sensors.........................................................3-24
Service........................................................... 5-3
Adding Equipment to the Outside of Your
Vehicle..................................................... 5-4
Doing Your Own Work................................... 5-3
Engine Soon Light.......................................3-36
Publications Ordering Information...................7-11
Vehicle Soon Light.......................................3-42
Service Bulletins.............................................7-12
Service Engine Soon Light...............................3-36
11