The following services should be performed at the first maintenance service (I or II) after the indicated miles (kilometers) shown for each item.
Service and Miles (Kilometers)  | 25,000 (41 500)  | 50,000 (83 000)  | 75,000 (125 000)  | 100,000 (166 000)  | 125,000 (207 500)  | 150,000 (240 000)  | 
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Inspect fuel system for damage or leaks.  | ·  | ·  | ·  | ·  | ·  | ·  | 
Inspect exhaust system for loose or damaged components.  | ·  | ·  | ·  | ·  | ·  | ·  | 
Vehicles without a filter restriction indicator: Replace engine air cleaner filter. See "Engine Air Cleaner/Filter" in your owner manual.  | 
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Change automatic transmission fluid and filter (except Acadia, Enclave, Equinox, and Torrent) (severe service) (except Allison Transmission®). See footnote (h).  | 
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Except HHR: Change automatic transmission fluid and filter (except Acadia, Enclave, Equinox, and Torrent) (normal service) (except Allison Transmission®).  | 
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All-wheel and four-wheel drive*: Change transfer case fluid (normal service for Silverado and Sierra). See footnotes (g) and (q).  | 
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Silverado and Sierra with four-wheel drive: Change transfer case fluid (extreme duty service). See footnotes (g), (p), and (q).  | ·  | ·  | ·  | ·  | ·  | ·  | 
Escalade, EXT, Avalanche, Silverado, Sierra, Tahoe, Yukon, Sierra Denali, Yukon Denali, Expres, and Savana: Inspect evaporative control system. An Emission Control Service. See footnotes † and (k).  | 
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Replace spark plugs. An Emission Control Service.  | 
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Except Colorado, Canyon, and HHR: Inspect spark plug wires**. An Emission Control Service.  | 
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Engine cooling system service (or every five years, whichever occurs first). An Emission Control Service. See footnote (i).  | 
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Inspect engine accessory drive belt. An Emission Control Service. See footnote (o).  | 
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* Trailblazer/Envoy: Automatic transfer case only.
** Trailblazer/Envoy: Inspect spark plug wires on V8 engine only.