GMC 1999 Sierra 1500 Pickup Owner's Manual page 394

6.2L AND 6.5L DIESEL ENGINES-
-0OTNOTES:
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Change filter every 15,000 miles (24 000 km), except when operating in dusty
conditions. Dusty conditions may require more frequent filter replacement. Extreme
dust and dirt operating conditions (off-road), may require the air filter to be
checked as often as every 300 miles (483 km) and replaced as necessary.
* An Emission Control Service
**
See "Explanation of Scheduled Maintenance Services" in this section.
1
Applicable only to trucks sold in the United States.
A Also, a Noise Control Service (applicable to vehicles with engine VIN Code J).
t
This maintenance schedule applies to all diesel engines available. TO330
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