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When to Change Engine Oil
If any one of these are 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.
How to Reset the CHANGE ENGINE
OIL Light
The GM Oil Life System calculates when to change your
engine oil andfilter 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 chang your oil prior to a CHANGE ENGINE OIL light
being turned on, reset the system.
To reset the CHANGE ENGINE 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 withinfive seconds.
3. If the CHANGE ENGINE OIL lightflashes for
five seconds, the system is reset.
If the system does not reset, try the procedure once
again. If it still does not reset, see your dealer for
service.
SeeChange Engine Oil Light on page 3-37.
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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 50,000 miles
(83,000 km) if the vehicle’s GVWR is over 8,600 or 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 your vehicle’s GVWR is not over 8,600 and you do
not use your vehicle under any of these conditions,
change thefluid andfilter every 100,000 miles
(166 000 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 littlefluid can damage
your transmission. Too much can mean that some
of thefluid could come out and fall on hot engine
part or exhaust system parts, starting afire.
Too littlefluid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmissionfluid.
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.
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Then, without shutting off the engine, follow these steps:
The transmission dipstick
is located near the center
of the engine compartment
and will be labeled with
this graphic shown.
SeeEngine Compartment Overview on page 5-12for
more information on location.
1. 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. Thefluid level must be in the COLD area for
a cold check or in the HOT area or cross-hatched
area for a hot check.
4. If thefluid level is in the acceptable range, push the
dipstick back in all the way; thenflip the handle
down to lock the dipstick in place.
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Notice:If your engine catchesfire because you keep
driving with no coolant, your vehicle can be badly
damaged. The costly repairs would not be covered by
your warranty. See“Overheated Engine Protection
Operating Mode”in the Index for information on
driving to a safe place in an emergency.
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”inTowing a
Trailer on page 4-31.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(N)
while stopped. If it is safe to do so, pull off the road,
shift to PARK (P) or NEUTRAL(N) 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, and you have not stopped,
pull over, stop, and park your vehicle right away.
If there’s still no sign of steam, 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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8. Then replace the pressure cap. At any time during
this procedure if coolant begins toflow out of the
filler neck, reinstall the pressure cap.
Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When the
clutch is engaged, the fan spins faster to provide more air
to cool the engine. In most everyday driving conditions,
the fan is spinning slower and the clutch is not fully
engaged. This improves fuel economy and reduces fan
noise. Under heavy vehicle loading, trailer towing and/or
high outside temperatures, the fan speed increases as
the clutch more fully engages. So you may hear an
increase in fan noise. This is normal and should not be
mistaken as the transmission slipping or making extra
shifts. It is merely the cooling system functioning properly.
The fan will slow down when additional cooling is not
required and the clutch partially disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
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After the tires have been rotated, adjust the front
and rear inflation pressures as shown on the
Certification/Tire label. Make certain that all wheel nuts
are properly tightened. See“Wheel Nut Torque”
underCapacities and Specifications on page 5-97.
{CAUTION:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make 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
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. See“Changing a Flat
Tire”in the Index.
When It Is Time for New Tires
One way to tell when it’s
time for new tires is to
check the treadwear
indicators, which will
appear when your tires
have only 1/16 inch
(1.6 mm) or less of tread
remaining. Some
commercial truck tires
may not have treadwear
indicators.
You need a new tire if any of the following statements
are true:
•You can see the indicators at three or more places
around the tire.
•You can see cord or fabric showing through the
tire’s rubber.
•The tread or sidewall is cracked, cut or snagged
deep enough to show cord or fabric.
•The tire has a bump, bulge or split.
•The tire has a puncture, cut or other damage that
can’t be repaired well because of the size or
location of the damage.
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Tire Chains
Notice:Use tire chains only where legal and only
when you must. Use chains that are the proper size
for your tires. Install them on the tires of the rear
axle. Tighten them as tightly as possible with
the ends securely fastened. Drive slowly and follow
the chain manufacturer’s instructions. If you can
hear the chains contacting your vehicle, stop
and retighten them. If the contact continues, slow
down until it stops. Driving too fast or spinning the
wheels with chains on will damage your vehicle.
If a Tire Goes Flat
It’s unusual for a tire to“blowout”while you’re driving,
especially if you maintain your tires properly. If air goes
out of a tire, it’s much more likely to leak out slowly.
But if you should ever have a“blowout”, here are a few
tips about what to expect and what to do:
If a front tire fails, theflat tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheelfirmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like a
skid and may require the same correction you’d use
in a skid. In any rear blowout, remove your foot from the
accelerator pedal. Get the vehicle under control by
steering the way you want the vehicle to go. It may be
very bumpy and noisy, but you can still steer. Gently
brake to a stop—well off the road if possible.
If a tire goesflat, the next part shows how to use your
jacking equipment to change aflat tire safely.
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Turn the ratchet counterclockwise to lower the spare tire
to the ground. If the spare tire does not lower to the
ground, the secondary latch is engaged causing the tire
not to lower. See“Secondary Latch System”later in
this section.When the tire has been lowered, pull the tire toward you
so you can reach the tire retainer and pull it up through
the wheel opening.
If you have a vehicle which was completed from a cab
and chassis, refer to the information from the body
supplier/installer.
The spare tire is a full-size tire, like the other tires on
your vehicle.
Notice:To help avoid vehicle damage, do not drive
the vehicle before the cable is restored.
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