2003 CHEVROLET C/K reset

6-25
As in the chart shown previously, SAE 5W-30 is best for
your vehicle. However, you can use SAE 10W
-30 if it's
going to be 0
F (
-18
C) or above. These numbers on
an oil container show its viscosity, or thickness. Do not
use other viscosity oils, such as SAE 20W
-50.
NOTICE:
Use only engine oil with the American Petroleum
Institute Certified 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 where the temperature falls
below
-20F (-29C), consider using 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
Don't add anything to your oil. The recommended oils
with the starburst symbol 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 filter. 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 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 filter must be changed at least once
a year and at this time the system must be reset. 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.

6-26
How to Reset the Change Oil Light
The GM Oil Life System
calculates when to change
your engine oil and filter 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
light being turned on, reset the system.
To reset the change oil light, do the following:
1. Turn the ignition key to RUN with the engine off.
2. Fully press and release the accelerator pedal three
times within 10 seconds.
If the change oil light flashes for five seconds, the
system is reset. If the light does not display for five
seconds, you will need to repeat the steps.What to Do with Used Oil
Used engine oil contains certain elements that may be
unhealthy for your skin and could even cause cancer.
Don't 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 throw away 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
filter 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.

6-31
The restriction indicator
is located in the engine
compartment near the
engine air cleaner/filter,
on the passenger's side of
the vehicle.
When the yellow indicator reaches the red ring in the
sight glass, it's time to service the engine air
cleaner/filter.
After the engine air cleaner/filter is properly serviced,
the indicator can be reset by pressing the button on top
of the indicator.
CAUTION:
Gasoline Engines Only: 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 stops flame if the engine
backfires. If it isn't there, and the engine
backfires, you could be burned. Don't drive with
it off, and be careful working on the engine with
the air cleaner/filter off.
NOTICE:
Gasoline Engines Only: If the air cleaner/filter is
off, a backfire can cause a damaging engine fire.
And, dirt can easily get into your engine, which
will damage it. Always have the air cleaner/filter
in place when you're driving.
Your vehicle may be equipped with an optional instrument
panel mounted air filter restriction indicator. See ªWarning
Lights, Gages and Indicatorsº in the Index.

6-39
Power Steering Fluid
See your Maintenance Schedule for when to check your
power steering fluid.
How To Check Power Steering Fluid
Check your power steering fluid only when the engine is
warm. If the engine isn't warm, you probably won't get
an accurate reading.
If the fluid level is
between the MIN and
MAX marks, you have
enough. If you need
fluid, add only enough
of the proper fluid to
bring it into view in
the sight glass.If your power steering fluid level is low, this can cause
the BRAKE or service brake soon warning lights to
come on. If either light remains on after you have added
power steering fluid to the proper level, then shut off the
engine for 10 seconds. This should reset the brake
warning lights. If one or both lights stay on though, see
ªHydraulic Brake Warning Lightsº in the Index.
What to Use
To determine what kind of fluid to use, see
ªRecommended Fluids and Lubricantsº in the Index.
NOTICE:
When adding power steering fluid or making a
complete fluid change, always use the proper
fluid. Failure to use the proper fluid can cause
leaks and damage hoses and seals.

6-62 Wheel Alignment and Tire Balance
The wheels on your vehicle were aligned at the factory
to give you the longest tire life and best overall
performance.
Proper front wheel alignment must be maintained in
order to ensure efficient steering, good directional
stability, and prevent abnormal tire wear. If you notice
unusual tire wear or your vehicle is pulling one way or
the other, the alignment may need to be reset. If you
notice your vehicle vibrating when driving on a smooth
road, your wheels may need to be balanced.
Tightening the Wheel Nuts
CAUTION:
Wheel nuts that are not tight can work loose. If
all the nuts on a wheel come off, the wheel can
come off the vehicle, causing a crash. All wheel
nuts must be properly tightened. Follow the rules
in this section to be sure they are.
This section lets you know how often to check the
tightness of the wheel nuts on your vehicle and how
tight they must be.
First, use these pictures to decide what kind of wheels
you have.

7-5
Scheduled Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be repeated after 100,000 miles
(166 000 km) at the same intervals for the life of
this vehicle. The services shown after 100,000 miles
(166 000 km) should be repeated at the same miles (km)
after those intervals for the life of this vehicle.
Gasoline engine vehicles have a computer that lets you
know when to change your engine oil. This is not based
on mileage, but on engine revolutions and engine
operating temperature. When the computer has
calculated that the oil needs changing, the GM Oil Life
System will indicate that a change is necessary.
The ªFootnotesº at the end of this Maintenance
Schedule further explain maintenance services.
See ªScheduled Maintenance Supplementsº earlier in
this section.
100 Miles (160 km)

Wheel stud nut service. (46)
1,000 Miles (1 600 km)

Wheel stud nut service. (46)

Rear axle air shift motor service.(11)

L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
7,500 Miles (12 000 km)

Gasoline Engine Only: Check Oil Life System.
If engine oil and filter are changed, reset system.
See ªEngine Oilº in the Index. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(6)

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Wheels and tires service. (15)

Parking brake service (or every 6 months, whichever
occurs first). (8)

L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
10,000 Miles (16 000 km)

DURAMAX Diesel Only: Change engine oil
and filter (or every 12 months, whichever
occurs first). (2)(3)

7-6
15,000 Miles (24 000 km)

Gasoline Engine Only: Check Oil Life System.
If engine oil and filter are changed, reset system.
See ªEngine Oilº in the Index. (3)(9)

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(6)

DURAMAX Diesel Only: Replace fuel filter.

Steering system service. (13)

Front and rear suspension service. (14)

Spring
-to-axle U-bolts and shackle bolts
service. (16)

Exhaust system service (or every 6 months,
whichever occurs first). (3)(4)(17)

Wheels and tires service. (15)

Hydraulic brake service (or every 6 months,
whichever occurs first). (7)(46)

Parking brake service (or every 6 months, whichever
occurs first). (8)

Thermostatically controlled engine cooling fan
service. (4)(20)

Shields and underhood insulation service. (4)(5)(21)

L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
20,000 Miles (32 000 km)

DURAMAX Diesel Only: Change engine oil
and filter (or every 12 months, whichever occurs
first). (2)(3)

Air compressor dry element pleated paper air strainer
service (or every 2 months or every 800 hours,
whichever occurs first).
22,500 Miles (36 000 km)

Gasoline Engine Only: Check Oil Life System.
If engine oil and filter are changed, reset system.
See ªEngine Oilº in the Index. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(6)

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Inspect door hinge pins and bushings and replace
as necessary.

Cooling system service. Clean the cooling system
filler cap with clean water, clean the core, pressure
test the cap and the system for proper pressure
capability and inspect condition of cooling and
heater hoses and clamps. Replace hoses if cracked,
swollen or damaged.

7-7
Wheel bearing (grease type) service (or every
24 months, whichever occurs first, and whenever
hubs are removed). (23)(46)
Wheels and tires service. (15)
Parking brake service (or every 6 months, whichever
occurs first). (8)
Air intake system service (or every 24 months,
whichever occurs first). (4)(5)(24)
Evaporative Control System service (if equipped) (or
every 24 months, whichever occurs first). (3)(26)

Rear axle air shift motor service. (11)
Air brake service (or every 6 months, whichever
occurs first). (39)
Air brake automatic slack adjuster service
(or every 500 hours, whichever occurs first). (40)
Check air brake relay valve operation and check
for leaks (or every month, or every 300 hours,
whichever occurs first).
Clean air brake application valve (or every 3 months,
or every 300 hours, whichever occurs first); lubricate
linkage.
Air brake chamber service (or every 2 months,
whichever occurs first). (41)Trailer brake hand control valve service (or every
3 months, or every 900 hours, whichever
occurs first). (42)
L18/LB7 Engines Only: Clutch pedal free
travel service. (10)
30,000 Miles (48 000 km)
Gasoline Engine Only: Check Oil Life System.
If engine oil and filter are changed, reset system.
See ªEngine Oilº in the Index. (3)(9)
DURAMAX Diesel Only: Change engine oil
and filter (or every 12 months, whichever occurs
first). (2)(3)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(6)
DURAMAX Diesel Only: Replace fuel filter.
Chassis lubrication service (or every 6 months,
whichever occurs first). (12)
Replace fuel filter(s) (or every 12 months, whichever
occurs first). (3)
Steering system service. (13)
Front and rear suspension service. (14)
Spring
-to-axle U-bolts and shackle bolts
service. (16)
Exhaust system service (or every 6 months,
whichever occurs first). (3)(4)(17)
(Continued)