1999 CHEVROLET SILVERADO oil change

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At approximately 265
F (130
C), the message center
will display a TRANS FLUID HOT message and the
transmission will enter a transmission protection mode.
When the transmission enters the protection mode, you
may notice a change in the transmission shifting
patterns. The transmission will return to normal shifting
patterns when the transmission fluid temperature falls
below 260
F (127
C).
See ªMessage Centerº in the Index for
further information.
If the transmission fluid reaches temperatures of
approximately 275
F (135
C) or greater, the message
center will display a TRANS HOT...IDLE ENG warning
message. Pull the vehicle off the roadway when it is safe
to do so. Set the parking brake, place the transmission in
PARK (P) and allow the engine to idle until the
transmission temperature falls below 260
F (127
C).
If the transmission continues to operate above 265
F
(130
C), please contact your nearest dealer or the
GM Roadside Assistance Center.
NOTICE:
If you keep driving your vehicle with the
transmission temperature gage above the normal
operating range, you can damage the
transmission. This could lead to costly repairs
that may not be covered under your warranty.
The following situations can cause the transmission to
operate at higher temperatures:

Towing a trailer

Hot outside air temperatures

Hauling a large or heavy load

Low transmission fluid level

High transmission fluid level

Restricted air flow to the radiator and the auxiliary
transmission oil cooler (if equipped).
A temporary solution to hotter transmission operating
temperatures may be to let the transmission cool down.
If the transmission is operated at higher temperatures on
a frequent basis, see ªScheduled Maintenanceº in the
Index for the proper transmission maintenance intervals.

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2-79
If so, your electrical system may be wet. The condition
will usually be corrected when the electrical system
dries out. A few driving trips should turn the light off.
Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel (see
ªFuelº in the Index). Poor fuel quality will cause your
engine not to run as efficiently as designed. You may
notice this as stalling after start
-up, stalling when you
put the vehicle into gear, misfiring, hesitation on
acceleration or stumbling on acceleration. (These
conditions may go away once the engine is warmed up.)
This will be detected by the system and cause the light
to turn on.
If you experience one or more of these conditions,
change the fuel brand you use. It will require at least one
full tank of the proper fuel to turn the light off.
If none of the above steps have made the light turn off,
have your dealer or qualified service center check the
vehicle. Your dealer has the proper test equipment and
diagnostic tools to fix any mechanical or electrical
problems that may have developed.
Oil Pressure Gage
The oil pressure gage shows
the engine oil pressure in
psi (pounds per square inch)
when the engine is
running. Canadian vehicles
indicate pressure in
kPa (kilopascals).
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but readings above the
low pressure zone indicate the normal operating range.
A reading in the low pressure zone may be caused by a
dangerously low oil level or some other problem
causing low oil pressure. Check your oil as soon as
possible. See ªCheck Eng Oil Pressureº and ªEngine
Oilº in the Index.

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2-86 CHANGE ENGINE OIL
This message is displayed
when the engine oil needs
to be changed. The message
is only displayed for
15 seconds at the start
of each ignition cycle.
When you change the engine oil, be sure to reset the
Engine Oil Life Monitor. See ªEngine Oil, When to
Changeº in the Index.
SECURITY
This message is
displayed when the
content theft
-deterrent
system has been activated
and also monitors the
Passlock

System.
If the security message is displayed continuously while
driving and stays on, there may be a problem with the
Passlock System. Your vehicle will not be protected by
Passlock, and you should see your GM dealer.
SERVICE 4WD (If Equipped)
If the SERVICE 4WD
message comes on, there
may be a problem with the
Automatic Transfer Case
and service is required.
Malfunctions can be indicated by the system before any
problem is apparent, which may prevent serious damage
to the vehicle. This system is also designed to assist
your service technician in correctly diagnosing
a malfunction.

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5-9
Engine Overheating
(Gasoline Engine)
You will find a coolant temperature gage on your
vehicle's instrument panel. See ªEngine Coolant
Temperature Gageº in the Index. In addition, you will
find a LOW COOLANT, CHECK COOLANT TEMP,
ENGINE OVERHEATED and a REDUCED ENGINE
POWER message in the message center on the
instrument panel. See ªMessage Centerº in the Index.
If your vehicle has a diesel engine, see ªEngine
Overheatingº in the Diesel Engine Supplement.
Overheated Engine Protection Operating
Mode (V8 Gasoline Engines Only)
Should an overheated engine condition exist and the
REDUCED ENGINE POWER message is displayed, an
overheat protection mode which alternates firing groups
of cylinders helps prevent engine damage. In this mode,
you will notice a loss in power and engine performance.
This operating mode allows your vehicle to be driven to
a safe place in an emergency. Towing a trailer in the
overheat protection mode should be avoided.
NOTICE:
After driving in the overheated engine protection
operating mode, to avoid engine damage, allow the
engine to cool before attempting any repair. The
engine oil will be severely degraded. Repair the
cause of coolant loss, change the oil and reset the
oil life monitor. See ªEngine Oilº in the Index.

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5-27
4. Remove all the wheel
nuts and take off the
flat tire.
5. Remove any rust or dirt
from the wheel bolts,
mounting surfaces and
spare wheel.
CAUTION:
Rust or dirt on the wheel, or on the parts to
which it is fastened, can make the wheel nuts
become loose after a time. The wheel could come
off and cause an accident. When you change a
wheel, remove any rust or dirt from the places
where the wheel attaches to the vehicle. In an
emergency, you can use a cloth or a paper towel
to do this; but be sure to use a scraper or wire
brush later, if you need to, to get all the rust or
dirt off.
CAUTION:
Never use oil or grease on studs or nuts. If you
do, the nuts might come loose. Your wheel could
fall off, causing a serious accident.

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6-14 What Kind of Engine Oil to Use
Oils recommended for your vehicle can be identified by
looking for the ªStarburstº 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 following chart:

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As shown in the chart, SAE 5W-30 is best for your
vehicle. However, you can use SAE 10W
-30 if it's going
to be 0F (
-18C) 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
ªStarburstº 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. Your dealer is ready to
advise if you think something should be added.
When to Change Engine Oil
Your vehicle has 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 Oil Life Monitor will indicate
that a change is necessary. The mileage between oil
changes will vary depending on how you drive your
vehicle
-- usually between 3,000 miles (5 000 km) and
7,500 miles (12 500 km) since your last oil change.
Under severe conditions, the indicator may come on
before 3,000 miles (5 000 km). Never drive your vehicle
more than 7,500 miles (12 500 km) or 12 months
(whichever occurs first) without an oil change.
The system won't detect dust in the oil. So, if you drive
in a dusty area, be sure to change your oil every
3,000 miles (5 000 km) or sooner. Remember to reset
the CHANGE ENGINE OIL message whenever the oil
is changed.

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How to Reset the CHANGE ENGINE OIL Message
To reset the CHANGE ENGINE OIL message, turn the
ignition key to RUN with the engine off. Fully press and
release the accelerator pedal three times within five
seconds. If the CHANGE ENGINE OIL message flashes
for five seconds, the system is reset.
What to Do with Used Oil
Did you know that 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 real threat to the environment. If you
change your own oil, be sure to drain all free
-flowing oil
from the filter before disposal. Don't ever 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.
Engine Air Cleaner/Filter
The air cleaner assembly
has an indicator that lets
you know when the air
filter is dirty and needs to
be serviced. The indicator
is located on the air
cleaner cover.
See ªOwner Checks and Servicesº in the Index to
determine when to check the indicator.
If the area inside the clear section of the indicator is not
completely yellow, no air filter service is required.
When the area inside the indicator is completely yellow,
past the red band, the words ªCHANGE FILTERº will
be highlighted. After changing the air filter, press the top
button on the indicator to reset it.