GMC TopKick 2007 Owner's Manual page 366

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). (34)
Thermostatically controlled engine cooling
fan service. (3) (19)
Shields and underhood insulation
service. (3) (4) (20)
Gasoline Engine: Air compressor remote
mounted air filter dry element pleated paper
air strainer service (or every 6 months or
every 1800 hours, whichever occurs first).
22,500 Miles (36 000 km)
Gasoline Engine Only: Check engine oil life
system. If engine oil and filter are changed,
reset system. See "Engine Oil (Gasoline
Engine)" in the Index. (2) (8)
Check fluid levels (or every 3 months,
whichever occurs first). (1) (5)
366
Chassis lubrication service (or every 6 months,
whichever occurs first). (11)
Inspect door hinge pins and bushings and
replace as necessary.
Cooling system service. Clean the cooling
system filter cap with clean water, clean
the core, pressure test the cap and the system
for proper pressure capability, and inspect
condition of cooling and heater hoses
and clamps. Replace hoses if cracked,
swollen, or damaged.
Wheels and tires service. (14)
Hydraulic brake service (or every 6 months,
whichever occurs first). (6) (36)
Parking brake service (or every 6 months,
whichever occurs first). (21)
Air brake service (or every 6 months,
whichever occurs first). (32)
Air brake automatic slack adjuster service (or
every 500 hours, whichever occurs first). (33)