GMC 1999 Sonoma, Owner'S Manual

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Refer to the Maintenance Schedule to determine when to
replace the air filter. See “Scheduled Maintenance
Services” in the Index.
CAUTION:
Operating the engine with the air cleaner/filter
off can cause you or others to be burned. The air
cleaner not only cleans the air, it stops flame if
the engine backfires. If it isn’t there, and the
engine backfires, you could be burned. Don’t
drive with it off, and be careful working on the
engine with the air cleaner/filter off.
NOTICE:
If the air cleaner/filter is off, a backfire can cause a
damaging engine fire. And, dirt can easily get into
your engine, which will damage it. Always have the
air cleaner/filter in place when you’re driving.
Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmission fluid
level is when the engine oil is changed.
Change both the fluid and filter every 15,000 miles
(25 000 km) if the vehicle is mainly driven under one or
more of these conditions:
D In heavy city traffic where the outside temperature
regularly reaches 90
_F (32_C) or higher.
D In hilly or mountainous terrain.
D When doing frequent trailer towing.
D Uses such as found in taxi, police or delivery service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter every
50,000 miles (83 000 km).
See “Scheduled Maintenance Services” in the Index.
How to Check
Because this operation can be a little difficult, you
may choose to have this done at the dealership
service department.