GMC Chevrolet Tahoe 2003 Manual page 397

As in the chart shown previously, SAE 5W-30 is the
only viscosity grade recommended for your vehicle. You
should look for and use only oils which have the API
Starburst symbol and which are also identified as
SAE 5W-30. If you cannot find such SAE 5W-30 oils,
you can use an SAE 10W-30 oil which has the API
Starburst symbol, if it's going to be 0°F (−18°C)
or above. Do not use other viscosity grade oils, such as
SAE 10W-40 or SAE 20W-50 under any conditions.
Notice: Use only engine oil with the American
Petroleum Institute Certified For Gasoline Engines
starburst symbol. Failure to use the recommended
oil can result in engine damage not covered by
your warranty.
®
GM Goodwrench oil meets all the requirements for
your vehicle.
If you are in an area of extreme cold, where the
temperature falls below −20°F (−29°C), it is
recommended that you use either an SAE 5W-30
synthetic oil or an SAE 0W-30 oil. Both will provide
easier cold starting and better protection for your engine
at extremely low temperatures.
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.
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