2003 GMC SONOMA automatic transmission

Selecting the Right Schedule
First you’ll need to decide which of the two schedules is
right for your vehicle. Here’s how to decide which
schedule to follow:
Short Trip/City Definition
Follow the Short Trip/City Scheduled Maintenance if any
one of these conditions is true for your vehicle:
•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.
If the vehicle is used for delivery service, police,
taxi or other commercial application.
One of the reasons you should follow this schedule if
you operate your vehicle under any of these conditions
is that these conditions cause engine oil to break
down sooner.
Short Trip/City Intervals
Every 3,000 Miles (5 000 km):Engine Oil and Filter
Change (or 3 months, whichever occursfirst). Chassis
Lubrication (or 3 months, whichever occursfirst).
Drive Axle Service.
Every 6,000 Miles (10 000 km):Tire Rotation.
Every 15,000 Miles (25 000 km):Engine Air Cleaner
Filter Inspection. Front Wheel Bearing Repack
(two-wheel drive only) (or at each brake relining,
whichever occursfirst). Automatic Transmission Service
(severe conditions only).
Every 30,000 Miles (50 000 km):Engine Air
Cleaner Filter Replacement. Fuel Filter Replacement
(4.3L V6 engine only).
Every 50,000 Miles (83 000 km):Automatic
Transmission Service (normal conditions).
Every 90,000 Miles (150 000 km):Fuel Filter
Replacement (2200 L4 engine only).
Every 100,000 Miles (166 000 km):Spark Plug Wire
Inspection. Spark Plug Replacement. 4.3L V6 Engine
Only: Positive Crankcase Ventilation (PCV) Valve
Inspection.
6-5
2003 - Sonoma OM

Every 150 000 Miles (240 000 km):Cooling System
Service (or every 60 months, whichever occurs
first). Engine Accessory Drive Belt Inspection.
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.
Long Trip/Highway Definition
Follow this scheduled maintenanceonlyif none of the
conditions from the Short Trip/City Scheduled
Maintenance are true. Do not use this schedule if the
vehicle is used for trailer towing, driven in a dusty area
or used off paved roads. Use the Short Trip/City
schedule for these conditions
Driving a vehicle with a fully warmed engine under
highway conditions will cause engine oil to break down
slower.
Long Trip/Highway Intervals
Every 7,500 Miles (12 500 km):Engine Oil and Filter
Change (or every 12 months, whichever occurs
first). Chassis Lubrication (or 12 months, whichever
occursfirst). Drive Axle Service. Tire Rotation.
Every 15,000 Miles (25 000 km):Engine Air Cleaner
Filter Inspection. Automatic Transmission Service
(severe conditions only).Every 30,000 Miles (50 000 km):Fuel Filter
Replacement (4.3L V6 engine only). Engine Air Cleaner
Filter Replacement. Front Wheel Bearing Repack
(two-wheel drive only) (or at each brake relining,
whichever occursfirst).
Every 50,000 Miles (83 000 km):Automatic
Transmission Service (normal conditions).
Every 90,000 Miles (150 000 km):Fuel Filter
Replacement (2200 L4 engine only).
Every 100,000 Miles (166 000 km):Spark Plug Wire
Inspection. Spark Plug Replacement. 4.3L V6 Engine
Only: Positive Crankcase Ventilation (PCV) Valve
Inspection.
Every 150,000 Miles (240 000 km):Cooling System
Service (or every 60 months, whichever occurs
first). Engine Accessory Drive Belt Inspection.
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.
6-6
2003 - Sonoma OM

❑Change automatic transmissionfluid andfilter 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 theuid andlter every 50,000 miles
(83 000 km).
18,000 Miles (30 000 km)
❑Change engine oil and lter (or every 3 months,
whichever occurs rst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs rst).(See footnote #.)
❑Check rear/front axle uid level and add uid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
21,000 Miles (35 000 km)
❑Change engine oil and lter (or every 3 months,
whichever occurs rst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs rst).(See footnote #.)
❑Check rear/front axle uid level and add uid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
24,000 Miles (40 000 km)
❑Change engine oil and lter (or every 3 months,
whichever occurs rst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occurs rst).(See footnote #.)
❑Check rear/front axle uid level and add uid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
6-9
2003 - Sonoma OM

27,000 Miles (45 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
30,000 Miles (50 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑For Two-Wheel-Drive vehicles only: Clean and
repack the front wheel bearings (or at each
brake relining, whichever occursrst).
❑4.3L V6 Engine Only: Replace fuellter.An Emission
Control Service. (See footnote†.)
❑Replace engine air cleanerlter. SeeEngine Air
Cleaner/Filter on page 5-18for more information.
An Emission Control Service.❑Change automatic transmissionuid andlter 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 theuid andlter every 50,000 miles
(83 000 km).
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
33,000 Miles (55 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
6-10
2003 - Sonoma OM

❑Change automatic transmissionuid andlter 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 theuid andlter every 50,000 miles
(83 000 km).
❑Inspect engine air cleanerlter. If necessary, replace
thelter. If vehicle is driven in dusty/dirty conditions,
inspectlter at every engine oil change. See
Engine Air Cleaner/Filter on page 5-18for more
information.An Emission Control Service. (See
footnote†.)
48,000 Miles (80 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
50,000 Miles (83 000 km)
❑If you haven’t used your vehicle under severe service
conditions listed previously and, therefore, haven’t
changed your automatic transmissionuid, change
both theuid andlter.
Manual transmissionuid doesn’t require change.
51,000 Miles (85 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
6-12
2003 - Sonoma OM

54,000 Miles (90 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
57,000 Miles (95 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
60,000 Miles (100 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑For Two-Wheel-Drive vehicles only: Clean and
repack the front wheel bearings (or at each
brake relining, whichever occursrst).
❑Change automatic transmissionuid andlter 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 theuid andlter every 50,000 miles
(83 000 km).
❑4.3L Engine Only: Replace fuellter.An Emission
Control Service. (See footnote†.)
❑Replace engine air cleanerlter. SeeEngine Air
Cleaner/Filter on page 5-18for more information.
An Emission Control Service.
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
6-13
2003 - Sonoma OM

75,000 Miles (125 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑For Two-Wheel-Drive vehicles only: Clean and
repack the front wheel bearings (or at each
brake relining, whichever occursrst).
❑Change automatic transmissionuid andlter 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 theuid andlter every 50,000 miles
(83 000 km).
❑Inspect engine air cleanerlter. If necessary, replace
thelter. If vehicle is driven in dusty/dirty conditions,
inspectlter at every engine oil change. SeeEngine
Air Cleaner/Filter on page 5-18for more information.
An Emission Control Service. (See footnote†.)❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
78,000 Miles (130 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
81,000 Miles (135 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
6-15
2003 - Sonoma OM

84,000 Miles (140 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
87,000 Miles (145 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)
❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
90,000 Miles (150 000 km)
❑Change engine oil andlter (or every 3 months,
whichever occursrst).An Emission Control Service.
❑Lubricate chassis components (or every 3 months,
whichever occursrst).(See footnote #.)❑Check rear/front axleuid level and adduid as
needed. Check constant velocity joints and axle seals
for leaking.(See footnote **.)
❑For Two-Wheel-Drive vehicles only: Clean and
repack the front wheel bearings (or at each
brake relining, whichever occursrst).
❑Change automatic transmissionuid andlter 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 theuid andlter every 50,000 miles
(83 000 km).
❑Replace fuellter.An Emission Control Service.
(See footnote†.)
❑Replace engine air cleanerlter. SeeEngine Air
Cleaner/Filter on page 5-18for more information.
An Emission Control Service.
❑Rotate tires. SeeTire Inspection and Rotation on
page 5-60for proper rotation pattern and additional
information.(See footnote +.)
6-16
2003 - Sonoma OM