Chevrolet 2008 T Series Owner's Manual page 252

Air brake automatic slack adjuster service (or every
500 hours, whichever occurs first). (27)
Check air brake relay valve operation and check for
leaks (or every month, or every 300 hours, whichever
occurs first).
Clean air brake application valve (or every 3 months,
or every 300 hours, whichever occurs first). Lubricate
linkage.
Air brake chamber service (or every 2 months,
whichever occurs first). (28)
Air brake system valve service (or every 3 months,
or every 900 hours, whichever occurs first). (31)
Air compressor dry element pleated paper air strainer
service (or every 2 months, or every 800 hours,
whichever occurs first).
Thermostatically controlled engine cooling fan
service. (3) (17)
Shields and underhood insulation service. (3) (4) (18)
Rear axle air shift motor service. (9)
Air intake system service (or every 24 months,
whichever occurs first). (3) (4) (20)
6-10
48,000 Miles (75 000 km)
Lubricate U-joints (or every 6 months, whichever
occurs first).
50,000 Miles (80 000 km)
Inspect air compressor discharge port (or every
6 months or every 1,800 hours, whichever
occurs first.)
52,500 Miles (84 000 km)
Check fluid levels (or every 3 months, whichever
occurs first). (1) (5)
Chassis lubrication service (or every 6 months,
whichever occurs first). (10)
Wheels and tires service. (13)
Hydraulic brake service (or every 6 months,
whichever occurs first). (6) (30)
Parking brake service (or every 6 months, whichever
occurs first). (7)
Air brake service (or every 6 months, whichever
occurs first). (26)
Air brake automatic slack adjuster service (or every
500 hours, whichever occurs first). (27)