2009 GMC Sierra 1500 Crew Cab Owner's Manual - Page 555

(l) Extreme Duty Service: Change transfer case fluid if the vehicle is mainly driven off-road in four-wheel drive. Vehicles used for farming, mining, forestry, Department of Natural Resources (DNR), and snow plowing occupations meet this definition. (m) Severe Duty Service: Change transfer case fluid if the vehicle is mainly driven under one or more of these conditions: − Frequent trailer towing. − Taxi, police, or delivery service. (n) Vehicles with diesel engine or with GVWR above 10,000 lbs (4 536 kg) only: Inspect shields for damage or looseness. Adjust or replace as required. This is a Noise Emission Control Service. Applicable to vehicles sold in the United States and recommended for vehicles sold in Canada. (p) If driving regularly under dusty conditions, inspect the filter or change indicator (if equipped) at each engine oil change. (q) Visually inspect belt for fraying, excessive cracks, or obvious damage. Replace belt if necessary. Owner Checks and Services These owner checks and services should be performed at the intervals specified to help ensure vehicle safety, dependability, and emission control performance. Your dealer/retailer can assist with these checks and services. Be sure any necessary repairs are completed at once. Whenever any fluids or lubricants are added to the vehicle, make sure they are the proper ones, as shown in Recommended Fluids and Lubricants on page 6-15. At the First 100, 1,000 and 6,000 Miles (160, 1 600 and 10 000 km) For vehicles with dual wheels, check dual wheel nut torque. For proper torque, see Capacities and Specifications on page 5-131. 6-11