2003 CHEVROLET C/K oil viscosity

2-19
Starting the Diesel Engine
If you have a Caterpillar diesel engine, also refer to your
Caterpillar
Diesel Engine Operation & Maintenance
Manual for starting procedure.
For vehicles with the DURAMAX diesel engine, also
see ªStarting Your DURAMAX Diesel Engineº
following.
To make starting easier in cold weather (below 32F or
0C), the proper viscosity engine oil should be used.
See ªEngine Oilº in the Index. It's also best to heat the
engine oil first. You can do this by using an engine
coolant heater.
NOTICE:
If you ever need to have your vehicle towed, see
the part of this manual that tells how to do it
without damaging your vehicle. See ªTowing
Your Vehicleº in the Index.
Restarting the Diesel Engine While Moving
(Automatic Transmission)
If you have to restart the engine while the vehicle is
moving, you'll first have to shift the automatic
transmission to NEUTRAL (N). This safety feature
prevents starting the engine when the transmission is
in a drive gear.
Stopping the Diesel Engine
If you have a Caterpillar diesel engine, see your
Caterpillar
Diesel Engine Operation &
Maintenance Manual.
1. Set the parking brake and shift to NEUTRAL (N)
or PARK (P).
2. Turn the ignition key to OFF.
If your vehicle has a two
-speed axle, see ªRear Axle,
Tw o
-Speed Electric Shift Controlº or ªRear Axle,
Tw o
-Speed Airshift Controlº in the Index.

2-87 Oil Pressure Gage
United States Canada
The engine oil pressure gage, on the lower right portion
of your instrument panel cluster, shows engine oil
pressure in psi (pounds per square inch) or in kPa
(kilopascals). Oil pressure may vary with outside
temperature and oil viscosity, but readings of 30 to
40 psi (205 to 275 kPa) on gasoline engines at operating
temperature and moderate road speeds are normal. If
you have a diesel engine, the normal operating range
should be between 35 and 70 psi (240 to 480 kPa).A reading in the low pressure zone may be caused by a
dangerously low oil level or other problem.
If you have a Caterpillar

diesel engine, also see your
Caterpillar
Operation & Maintenance Manual.
CAUTION:
Don't keep driving if the oil pressure is low. If
you do, your engine can become so hot that it
catches fire. You or others could be burned.
Check your oil as soon as possible and have your
vehicle serviced.
NOTICE:
Damage to your engine from neglected oil
problems can be costly and is not covered by
your warranty.

6-24 What Kind of Engine Oil to Use
Oils recommended for your vehicle can be identified by
looking for the starburst symbol.
This symbol indicates that the oil has been certified by
the American Petroleum Institute (API). Do not use any
oil which does not carry this starburst symbol.
If you change your own oil,
be sure you use oil that has
the starburst symbol on the
front of the oil container.
If you have your oil
changed for you, be sure
the oil put into your engine
is American Petroleum
Institute certified for
gasoline engines.
You should also use the proper viscosity oil for your
vehicle, as shown in the viscosity chart.

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.

6-29

SAE 15W-40
As shown in the viscosity chart, SAE 15W
-40 is
best for your vehicle. However, you can use SAE
10W
-30 at temperatures above 0F (-18C).
When it's very cold, below 0F (
-18C), you should
use SAE 5W
-40 to improve cold starting.
These numbers on the oil container show its
viscosity, or thickness. Do not use other viscosity
oils such as SAE 10W
-40 or SAE 20W-50.
This doughnut-shaped logo
(symbol) is used on most
oil containers to help you
select the correct oil. It
means that the oil has been
certified by the American
Petroleum Institute.
You should look for this on the oil container, and use
only those oils that display the logo.
GM Goodwrench
 oil of the recommended viscosity
grades meets all the requirements for your vehicle.

7-27
Part C: Recommended Fluids and
Lubricants
Fluids and lubricants identified below by name,
part number or specification may be obtained from
your dealer.
USAGE
FLUID/LUBRICANT
Engine Oil
(Gasoline
Engine)Engine oil with the American
Petroleum Institute Certified for
Gasoline Engines starburst symbol
of the proper viscosity. To
determine the preferred viscosity
for your vehicle's engine, see
ªEngine Oilº in the Index.
Engine Oil
(Caterpillar
Diesel Engine)See the Caterpillar
Operation &
Maintenance Manual for engine
oil recommendations.
USAGEFLUID/LUBRICANT
Engine Coolant
(Gasoline
Engine &
DURAMAX
Diesel)50/50 mixture of clean, drinkable
water and use only DEX
-COOL

Coolant. See ªEngine Coolantº in
the Index.
Engine Coolant
(Caterpillar
Diesel Engine)See the Caterpillar
Operation &
Maintenance Manual for engine
coolant recommendations.
Hydraulic Brake
SystemDelco Supreme 11
Brake Fluid
or equivalent DOT
-3 brake fluid.
Windshield
Washer SolventGM Optikleen
Washer Solvent
or equivalent.
Clutch Bearing
LubricantClutch Bearing Lubricant
(GM Part No. 12378484 or
equivalent NLGI #3 consistency).