Engine Oil Additives; When To Change Engine Oil; Gm Oil Life System - GMC 2003 DURAMAX Owner's Manual

Engine Oil Additives

Don't 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

(GM Oil Life System)

Your vehicle has a computer system that lets you
know when to change the engine oil and filter. This is
based on engine revolutions, engine temperature and
on a maximum mileage of 10,000 miles (16 000 km).
Under severe conditions, the system may come
on before 10,000 miles (16 000 km). For the oil life
system to work properly, you must reset the system
every time the oil is changed.
When the system has calculated that oil life has been
diminished, it will indicate that an oil change is necessary.
A CHANGE ENGINE OIL message will come on. Change
your oil as soon as possible within the next two times you
stop for fuel. 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.
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