Engine Oil Life System - GMC 2005 T-Series Owner's Manual

Engine Oil Additives
Do not add anything to your oil. The recommended oils
with the API service symbol are all you will need for
good performance and engine protection.
When to Change Engine Oil (Vehicles
Without the Engine Oil Life System)
Change engine oil and filter every 12,000 miles
(20 000 km), or every 12 months, or every 600 hours of
engine operation, whichever occurs first. See
Scheduled Maintenance on page 6-5.

Engine Oil Life System

When to Change Engine Oil
If your vehicle has the Engine Oil Life System, it has a
computer system that lets you know when to change
the engine oil and filter. This is based on injection timing,
engine load and engine temperature, and not on
mileage. Based on driving conditions, the mileage at
which an oil change will be indicated can vary
considerably. For the oil life system to work properly,
you must reset the system every time the oil is changed.
5-18
When the system has calculated that oil life has been
diminished, it will indicate that an oil change is necessary.
A change engine oil light will come on. See Change
Engine Oil Light on page 3-34. Change your oil as soon
as possible within the next 600 miles (1 000 km) or
30 hours of engine operation, whichever occurs first. It is
possible that, if you are driving under the best conditions,
the oil life system may not indicate that an oil change is
necessary for over a year. However, your engine oil and
filter must be changed at least once a year and at this
time the system must be reset. Your dealer has
GM-trained service people who will perform this work
using genuine GM parts and reset the system. It is also
important to check your oil regularly and keep it at the
proper level.
If the system is ever reset accidentally, you must
change your oil at 3,000 miles (5 000 km), or 150 hours
of engine operation, whichever occurs first, since
your last oil change. Remember to reset the oil life
system whenever the oil is changed.