Special Application Services

• Allison Transmission™ Vehicles Only: Replace external transmission filter at first engine oil change only.
• Vehicles with Dual Wheels: Check dual wheel nut torque at 160 km/100 mi, 1 600 km/ 1,000 mi and 9 700 km/6,000 mi.
• Severe Commercial Use Vehicles Only: Lubricate chassis components every 5 000 km/ 3,000 mi.
• Have underbody flushing service performed once a year.

    See also:

    Customer Assistance Offices (U.S. and Canada)
    GMC encourages customers to call the toll-free number for assistance. However, if a customer wishes to write or e-mail GMC, the letter should be addressed to: United States GMC Customer Assistance ...

    Filling the Tank
    WARNING Fuel vapor burns violently and a fuel fire can cause bad injuries. To help avoid injuries to you and others, read and follow all the instructions on the fuel pump island. Turn off the eng ...

    Engine Oil Change
    When the CHANGE ENGINE OIL SOON message displays, have the engine oil and filter changed within the next 1 000 km/600 mi. If driven under the best conditions, the engine oil life system might not ...