engine GMC SUBURBAN 1999 Owners Manual

6-11
When to Add Engine Oil
If the oil is at or below the ADD mark, then you'll need
to add at least one quart of oil. But you must use the
right kind. This part explains what kind of oil to use. For
crankcase capacity, see ªCapacities and Specificationsº
in the Index.
NOTICE:
Don't 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.
The engine oil fill cap for
the VORTEC 4800, 5300
and 6000 V8 engines is
located on the passenger's
side engine valve cover.
Be sure to fill it enough to put the level somewhere in
the proper operating range. Push the dipstick all the way
back in when you're through.

6-12 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 following chart:

6-13
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 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
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 GM Oil Life System will
indicate that a change is necessary. The mileage between
oil and filter 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 and filter change. Under severe conditions, the
system 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
and filter every 3,000 miles (5 000 km) or sooner.
Remember to reset the CHANGE ENGINE OIL
whenever the oil is changed.

6-14
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.

6-15
Your air cleaner is located in the passenger's side front
corner of the engine compartment.1. To remove the air filter, loosen the screws on the
cover. Then lift the cover upward and remove the
filter out of the air cleaner housing. Care should be
taken to dislodge as little dirt as possible.
2. Clean the filter sealing surface and the filter housing.
3. Install the new filter.
4. Install the cover and tighten the screws on the air
cleaner cover.
Refer to the Maintenance Schedule to determine when to
replace the air filter. See ªOwner Checks and Servicesº
in the Index.

6-16
CAUTION:
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:
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.
Passenger Compartment Air Filter
(If Equipped)
Your vehicle may be equipped with a passenger
compartment air filter. The filter is located under the
instrument panel below the glove compartment.
To replace the passenger compartment air filter:
1. If your vehicle is equipped with an access panel
located under the center of the instrument panel,
remove the bolts on it to take out the panel.
Because this operation can be a little difficult,
you may choose to have it done at your dealer's
service department.
2. If your vehicle does
not have an access
panel under the center
of the instrument panel,
or when the panel is
removed, reach under
the instrument panel
towards the front of
the vehicle and pull
downward on the filter
retaining bracket.

6-17
3. Remove the air filter by pulling downward on the
element. Remove the second portion of the air filter
by sliding it towards the rear of the vehicle and then
pulling downward.
4. Install the new filter by reversing the steps listed
previously. Be sure to follow any instructions that
may be included in the replacement filter package.
Refer to the Maintenance Schedule to determine
when to replace the passenger compartment air filter.
See ªScheduled Maintenanceº in the Index.
Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmission
fluid level is when the engine oil is changed.
Change both the fluid and filter 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 90F (32C) or higher.

In hilly or mountainous terrain.

When doing frequent trailer towing.

Uses such as found in taxi, police or delivery service.If you do not use your vehicle under any of
these conditions, change the fluid and filter every
100,000 miles (166 000 km).
See ªScheduled Maintenance Servicesº in the Index.
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 fluid can damage your
transmission. Too much can mean that some of
the fluid could come out and fall on hot engine
parts or exhaust system parts, starting a fire.
Be sure to get an accurate reading if you check
your transmission fluid.

6-18
Wait at least 30 minutes before checking the
transmission fluid level if you have been driving:

When outside temperatures are above 90F (32C).

At high speed for quite a while.

In heavy traffic
-- especially in hot weather.

While pulling a trailer.
To get the right reading, the fluid should be at
normal operating temperature, which is 180F to
200F (82C to 93C).
Get the vehicle warmed up by driving about 15 miles
(24 km) when outside temperatures are above
50F (10C). If it's colder than 50F (10C),
drive the vehicle in THIRD (3) until the engine
temperature gage moves and then remains steady
for 10 minutes. Then follow the hot check procedures.Checking Transmission Fluid Cold
A cold check is made after the vehicle has been sitting
for eight hours or more with the engine off and is used
only as a reference. Let the engine run at idle for five
minutes if outside temperatures are 50F (10C) or
more. If it's colder than 50F (10C), you may have
to idle the engine longer. Should the fluid level be low
during a cold check, you must perform a hot check
before adding fluid. This will give you a more accurate
reading of the fluid level.
Checking the Fluid Level
Prepare your vehicle as follows:

Park your 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 minutes or more.

6-19
Then, without shutting off the engine, follow these steps:
1. The red transmission dipstick handle is located at the
rear of the engine compartment, on the passenger's
side. Flip the handle up and then pull out the dipstick
and wipe it with a clean rag or paper towel.
2. Push it back in all the way, wait three seconds and
then pull it back out again.
3. Check both sides of the dipstick, and read the lower
level. The fluid level must be in the COLD area,
below the cross
-hatched area, for a cold check or in
the HOT area or cross
-hatched area for a hot check.
4. If the fluid level is in the acceptable range, push the
dipstick back in all the way; then flip the handle
down to lock the dipstick in place.

6-22 Front Axle
When to Check Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant. See ªScheduled Maintenance
Servicesº in the Index.
How to Check Lubricant
If the level is below the bottom of the filler plug hole,
you may need to add some lubricant.When the differential is cold, add enough lubricant
to raise the level to 1/2 inch (12 mm) below the filler
plug hole.
When the differential is at operating temperature
(warm), add enough lubricant to raise the level to
the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids
and Lubricantsº in the Index.
Engine Coolant
The cooling system in your vehicle is filled with
DEX
-COOL
engine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs first, if you add only
DEX
-COOL
extended life coolant.
The following explains your cooling system and how
to add coolant when it is low. If you have a problem
with engine overheating, see ªEngine Overheatingº
in the Index.