2003 GMC SONOMA service

Notice:Yourvehicle was not designed for fuel that
contains methanol. Don’t use fuel containing
methanol. It can corrode metal parts in your fuel
system and also damage the plastic and rubber parts.
That damage wouldn’t be covered under your
warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask the attendant where you buy gasoline
whether the fuel contains MMT. General Motors does
not recommend the use of such gasolines. Fuels
containing MMT can reduce the life of spark plugs and
the performance of the emission control system may
be affected. The malfunction indicator lamp may turn on.
If this occurs, return to your authorized GM dealer for
service.
Fuels in Foreign Countries
If you plan on driving in another country outside the
United States or Canada, the proper fuel may be hard
tofind. Never use leaded gasoline or any other fuel
not recommended in the previous text on fuel. Costly
repairs caused by use of improper fuel wouldn’tbe
covered by your warranty.
To check the fuel availability, ask an auto club, or
contact a major oil company that does business in the
country where you’ll be driving.
Filling Your Tank
{CAUTION:
Fuel vapor is highly ammable. It burns
violently, and that can cause very bad injuries.
Don’t smoke if you’re near fuel or refueling
your vehicle. Keep sparks, ames and smoking
materials away from fuel.
The fuel cap is located behind a hinged door on the
driver’s side of your vehicle.
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2003 - Sonoma OM

If you have the 2200 L4
engine, the engine oilfill
cap is located in the rear
of the engine compartment
on the passenger’s side
of the vehicle. If you have
the 4300 V6 engine, it
is located in the rear of the
engine compartment on
the driver’s side of
the vehicle.
Be sure tofill it enough to put the level somewhere in
the proper operating range. Push the dipstick all the way
back in when you’re through.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 choose to perform
the engine oil change
service yourself, be sure
the oil you use 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.
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2003 - Sonoma OM

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
If any one of these is true for you, use the short trip/city
maintenance schedule:
•Most trips are less than 5 miles (8 km). This is
particularly important when outside temperatures
are below freezing.
•Most trips include extensive idling (such as
frequent driving in stop-and-go traffic).
•You frequently tow a trailer or use a carrier on
top of your vehicle.
•The vehicle is used for delivery service, police,
taxi or other commercial application.Driving under these conditions causes engine oil to
break down sooner. If any one of these is true for your
vehicle, then you need to change your oil andfilter
every 3,000 miles (5 000 km) or 3 months—whichever
occursfirst.
If none of them is true, use the long trip/highway
maintenance schedule. Change the oil andfilter every
7,500 miles (12 500 km) or 12 months—whichever
occursfirst. Driving a vehicle with a fully warmed engine
under highway conditions will cause engine oil to
break down slower.
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2003 - Sonoma OM

Remote Oil Filter (Four-Wheel Drive)
The access door for the
remote oilfilter is in the
steering linkage shield
assembly located under
the radiator support.
Turn the screw to unlock
or lock the door. Make
sure if you open the door,
it is securely closed
when you arefinished.
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 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
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.
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2003 - Sonoma OM

Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmissionfluid
level is when the engine oil is changed.
Change both thefluid andfilter every 15,000 miles
(25 000 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 you do not use your vehicle under any of these
conditions, change thefluid andfilter every
50,000 miles (83 000 km).
SeePart A: Scheduled Maintenance Services
on page 6-4.
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 littleuid can damage
your transmission. Too much can mean that some
of theuid could come out and fall on hot engine
part or exhaust system parts, starting are.
Too littleuid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmissionuid.
Wait at least 30 minutes before checking the
transmissionfluid 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, thefluid should be at normal
operating temperature, which is 180°Fto200°F
(82°Cto93°C)
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2003 - Sonoma OM

Manual Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
changed. However, thefluid in your manual transmission
doesn’t require changing.
How to Check
Because this operation can be a little difficult, you may
choose to have this done at your GM dealership
service department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading.
Notice:Too much or too littleuid can damage
your transmission. Too much can mean that some
of theuid could come out and fall on hot engine
part or exhaust system parts, starting are.
Too littleuid could cause the transmission to
overheat. Be sure to get an accurate reading if
you check your transmissionuid.
Check thefluid level only when your engine is off, the
vehicle is parked on a level place and the transmission
is cool enough for you to rest yourfingers on the
transmission case.Then, follow these steps:
1. Remove thefiller plug.
2. Check that the lubricant level is up to the bottom of
thefiller plug hole.
3. If thefluid level is good, install the plug and be sure
it is fully seated. If thefluid level is low, add more
fluid as described in the next steps.
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2003 - Sonoma OM

How to Add Fluid
Here’s how to addfluid. Refer to the Maintenance
Schedule to determine what kind offluid to use.
SeePart D: Recommended Fluids and Lubricants on
page 6-33.
1. Remove thefiller plug.
2. Addfluid at thefiller plug hole. Add only enough
fluid to bring thefluid level up to the bottom of the
filler plug hole.
3. Install thefiller plug. Be sure the plug is fully
seated.
Hydraulic Clutch
The hydraulic clutch linkage in your vehicle is
self-adjusting. The clutch master cylinder reservoir is
filled with hydraulic clutchfluid.
It is not necessary to regularly check clutchfluid unless
you suspect there is a leak in the system. Adding
fluid won’t correct a leak.
Afluid loss in this system could indicate a problem.
Have the system inspected and repaired.
When to Check and What to Use
Refer to the Maintenance Schedule to determine how
often you should check thefluid level in your clutch
master cylinder reservoir and for the properfluid.
SeePart B: Owner Checks and Services on page 6-26
andPart D: Recommended Fluids and Lubricants
on page 6-33.
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2003 - Sonoma OM

If No Steam Is Coming From Your
Engine
If you get an engine overheat warning but see or hear
no steam, the problem may not be too serious.
Sometimes the engine can get a little too hot when you:
•Climb a long hill on a hot day.
•Stop after high-speed driving.
•Idle for long periods in traffic.
•Tow a trailer. See“Driving on Grades”under
Towing a Trailer on page 4-51.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. In heavy traffic, let the engine idle in NEUTRAL
while stopped. If it is safe to do so, pull off the
road, shift to PARK (P) or NEUTRAL and let the
engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning doesn’t come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there’s still no sign of steam, idle the engine for three
minutes while you’re parked. Push down the accelerator
until the engine speed is about twice as fast as normal
idle speed for at least three minutes while you’re parked.
If you still have the warning,turn off the engine and get
everyone out of the vehicleuntil it cools down.
You may decide not to lift the hood but to get service
help right away.
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2003 - Sonoma OM