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

Substitute Engine Oil: When adding oil to maintain
engine oil level, oil meeting GM Standard GM4718M
may not be available. You can add substitute oil
designated SAE 5W-30 with the starburst symbol at all
temperatures. If temperatures are above 0°F (-18°C),
you may substitute SAE 10W-30 with the starburst
symbol. Substitute oil not meeting GM Standard
GM4718M should not be used for an oil change.

Engine Oil Additives

Don't add anything to your oil. The recommended oils
with the starburst 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 that lets you know when to
change your engine oil and filter. This is based on
engine revolutions 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.
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When the system has calculated that oil life has been
diminished, it will indicate that an oil change is
necessary. A CHANGE OIL SOON 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.
If the system is ever reset accidentally, you must
change your oil at 3,000 miles (5 000 km) since your
last oil change. Remember to reset the oil life system
whenever the oil is changed.