GMC 2003 Sonoma Owner's Manual page 381

93,000 Miles (155 000 km)
Change engine oil and filter (or every 3 months,
whichever occurs first). An Emission Control Service.
Lubricate chassis components (or every 3 months,
whichever occurs first). (See footnote #.)
Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking. (See footnote **.)
96,000 Miles (160 000 km)
Change engine oil and filter (or every 3 months,
whichever occurs first). An Emission Control Service.
Lubricate chassis components (or every 3 months,
whichever occurs first). (See footnote #.)
Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking. (See footnote **.)
Rotate tires. See Tire Inspection and Rotation on
page 5-64 for proper rotation pattern and additional
information. (See footnote +.)
99,000 Miles (165 000 km)
Change engine oil and filter (or every 3 months,
whichever occurs first). An Emission Control Service.
Lubricate chassis components (or every 3 months,
whichever occurs first). (See footnote #.)
Check rear/front axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking. (See footnote **.)
100,000 Miles (166 000 km)
Inspect spark plug wires. An Emission Control
Service.
Replace spark plugs. An Emission Control Service.
If you haven't used your vehicle under severe service
conditions listed previously and, therefore, haven't
changed your automatic transmission fluid, change
both the fluid and filter.
Manual transmission fluid doesn't require change.
4.3L V6 Engine Only: Inspect Positive Crankcase
Ventilation (PCV) valve. An Emission Control
Service.
150,000 Miles (240 000 km)
Drain, flush and refill cooling system (or every
60 months since last service, whichever occurs first).
See Engine Coolant on page 5-27 for what to use.
Inspect hoses. Clean radiator, condenser, pressure
cap and neck. Pressure test cooling system and
pressure cap. An Emission Control Service.
Inspect engine accessory drive belt. An Emission
Control Service.
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