2004 BUICK CENTURY Owner's Manual

A. Windshield Washer Fluid Reservoir. SeeWindshield
Washer Fluid on page 5-36.
B. Battery. SeeBattery on page 5-41.
C. Underhood Fuse Block. SeeFuses and Circuit
Breakers on page 5-97.
D. Remote Positive (+) Battery Terminal. SeeJump
Starting on page 5-42.
E. Radiator Pressure Cap. SeeRadiator Pressure Cap
on page 5-25.
F. Engine Coolant Recovery Tank. SeeEngine Coolant
on page 5-22.
G. Power Steering Fluid Reservoir. SeePower Steering
Fluid on page 5-35.
H. Electric Engine Cooling Fan. SeeJump Starting on
page 5-42.
I. Engine Oil Fill Cap. SeeEngine Oil on page 5-13.
J. Engine Oil Dipstick. SeeEngine Oil on page 5-13.
K. Automatic Transaxle Fluid Dipstick. SeeAutomatic
Transaxle Fluid on page 5-19.
L. Brake Fluid Reservoir. SeeBrakes on page 5-38.
M. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 5-18.Engine Oil
Checking Engine Oil
It is a good idea to check your engine oil every time you
get fuel. In order to get an accurate reading, the oil
must be warm and the vehicle must be on level ground.
The engine oil dipstick handle is a yellow loop. See
Engine Compartment Overview on page 5-12for
the location of the engine oil dipstick.
Turn off the engine and give the oil several minutes to
drain back into the oil pan. If you don’t, the oil
dipstick might not show the actual level.
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.
5-13

When to Add Engine Oil
If the oil is at or below the cross-hatched area at the tip
of the dipstick, then you will need to add at least one
quart of oil. But you must use the right kind. This section
explains what kind of oil to use. For engine oil
crankcase capacity, seeCapacities and Specications
on page 5-103.
Notice:Do not add too much oil. If your engine has
so much oil that the oil level gets above the
cross-hatched area that shows the proper operating
range, your engine could be damaged.
SeeEngine Compartment
Overview on page 5-12for
the location of the
engine oil ll cap.Be sure to add enough oil to put the level somewhere in
the proper operating range in the cross-hatched area.
Push the dipstick all the way back in when you are
through.
What Kind of Engine Oil to Use
Look for two things:
GM6094M
Your vehicle’s engine requires oil meeting GM
Standard GM6094M. You should look for and use
only an oil that meets GM Standard GM6094M.
5-14

SAE 5W-30
As shown in the viscosity chart, SAE 5W-30 is best
for your vehicle. However, if it is going to be 0°F
(–18°C) or above and SAE 5W-30 is not available,
you may use SAE 10W-30.
These numbers on an oil container show its
viscosity, or thickness. Do not use other viscosity
oils such as SAE 20W-50.
Oils meeting these
requirements should also
have the starburst
symbol on the container.
This symbol indicates
that the oil has been
certied by the American
Petroleum Institute (API).
You should look for this information on the oil container,
and useonlythose oils that are identied as meeting
GM Standard GM6094M and have the starburst symbol
on the front of the oil container.
5-15

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

Engine Air Cleaner/Filter
SeeEngine Compartment Overview on page 5-12for
location of engine air cleaner/lter.
When to Inspect the Engine Air
Cleaner/Filter
Inspect the air cleaner/lter at every oil change
and replace at the rst oil change after 25,000 miles
(40 000 km).
How to Inspect the Engine Air
Cleaner/Filter
To inspect the air cleaner/lter remove it from the
vehicle and lightly shake the lter to release loose dust
and dirt. If the lter remains caked with dirt, a new
lter is required.
To check or replace the engine air cleaner/lter, do the
following:
1. Loosen the screw and clamp on the air duct.2. Lift the two clips
located on the top of
the lter assembly
to unlock the cover.
3. Disconnect the duct and reposition it while removing
the cover.
4. Pull out the lter.
5. Inspect or replace the lter if needed.
6. Reinstall the lter.
7. Push the two clips located on top of the lter
assembly to lock the cover.
5-18

{CAUTION:
Operating the engine with the air cleaner/lter
off can cause you or others to be burned. The
air cleaner not only cleans the air, it helps to
stop ame if the engine backres. If it is not
there and the engine backres, you could
be burned. Do not drive with it off, and be
careful working on the engine with the air
cleaner/lter off.
Notice:If the air cleaner/lter is off, a backre can
cause a damaging engine re. And, dirt can
easily get into your engine, which will damage it.
Always have the air cleaner/lter in place when you
are driving.
Automatic Transaxle Fluid
When to Check and Change
A good time to check the automatic transaxle uid level
is when the engine oil is changed.
Change both the uid and lter every 50,000 miles
(83 000 km) if the vehicle is mainly driven under one or
more of these conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police or delivery
service.
If the vehicle is not used under any of these conditions,
change the uid and lter at 100,000 miles
(166 000 km).
SeeScheduled Maintenance on page 6-4.
5-19

How to Check
Because this operation can be a little difficult, you may
choose to have this done at the dealership service
department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little uid can damage the
transaxle. Too much can mean that some of the
uid could come out and fall on hot engine or
exhaust system parts, starting a re. Too little uid
could cause the transaxle to overheat. Be sure
to get an accurate reading if you check the transaxle
uid.
Wait at least 30 minutes before checking the transaxle
uid level if you have been driving:
When outside temperatures are above 90°F (32°C).
At high speed for quite a while.
In heavy traffic – especially in hot weather.
While pulling a trailer.To get the right reading, the uid should be at
normal operating temperature, which is 180°F
to 200°F (82°C to 93°C).
Get the vehicle warmed up by driving about 15 miles
(24 km) when outside temperatures are above 50°F
(10°C). If it is colder than 50°F (10°C), you may have to
drive longer.
Checking the Fluid Level
Prepare the vehicle as follows:
Park the vehicle on a level place. Keep the engine
running.
With the parking brake applied, place the shift lever
in PARK (P).
With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, position the shift
lever in PARK (P).
Let the engine run at idle for three to ve minutes.
Then, without shutting off the engine, follow these steps:
5-20