For 1990-2009 cars

The following services should be performed at the first maintenance service (I or II) after the indicated miles (kilometers) shown for each item.

#### Additional Required Services

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)
--- | --- | --- | --- | --- | --- | ---
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. |  | · |  | · |  | ·
Change automatic transmission fluid and filter (except Acadia, Enclave, Equinox, and Torrent) (severe service) (except Allison Transmission®). See footnote (h). |  | · |  | · |  | ·
Except HHR: Change automatic transmission fluid and filter (except Acadia, Enclave, Equinox, and Torrent) (normal service) (except Allison Transmission®). |  |  |  | · |  |
All-wheel and four-wheel drive*: Change transfer case fluid (normal service for Silverado and Sierra). See footnotes (g) and (q). |  | · |  | · |  | ·
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). |  | · |  | · |  | ·
Replace spark plugs. An Emission Control Service. |  |  |  | · |  |
Except Colorado, Canyon, and HHR: Inspect spark plug wires**. An Emission Control Service. |  |  |  | · |  |
Engine cooling system service (or every five years, whichever occurs first). An Emission Control Service. See footnote (i). |  |  |  |  |  | ·
Inspect engine accessory drive belt. An Emission Control Service. See footnote (o). |  |  |  |  |  | ·

* Trailblazer/Envoy: Automatic transfer case only.

** Trailblazer/Envoy: Inspect spark plug wires on V8 engine only.