Chevrolet kodiak 2004 Owner's Manual page 234

What Kind of Engine Oil to Use
Look for these two things:
•
CI-4 or CH-4
Oils designated as API CI-4 or CH-4 are
recommended for your vehicle. The CI-4 or CH-4
designations may appear either alone, together or in
combination with other API designations, such as
API CI-4/SL.
These letters show American Petroleum
Institute (API) levels of quality.
Notice: If you use oil that does not have this
designation, CH-4, you can cause engine damage
not covered by your warranty.
Notice: Use only engine oils that have one of these
designations CI-4 or CH-4 for the DURAMAX™ diesel
engine. Failure to use the recommended oils can
result in engine damage not covered by your
warranty.
5-28
•
SAE 15W-40
As shown in the viscosity chart, SAE 15W-40 is
best for your vehicle. However, you can use
SAE 10W-30 at temperatures above 0°F (−18°C).
When it is very cold, below 0°F (−18°C), you should
use SAE 5W-40 to improve cold starting.
These numbers on the oil container show its
viscosity, or thickness. Do not use other viscosity
oils such as SAE 10W-40 or SAE 20W-50.
You should look for this on the oil container, and use
only those oils that display this logo.
®
GM Goodwrench oil of the recommended viscosity
grades meets all the requirements for your vehicle.
This doughnut-shaped
logo (symbol) is used on
most oil containers to
help you select the correct
oil. It means that the oil
has been certified by
the American Petroleum
Institute.