The recommended oil type on Your 2008 GMC Sierra is SAE 5W-30. If in case You live in an area where the temperature goes low 20 F then it is recommended to use SAE 0W-30. Your dealer recommends to use GM certified oil, if it isn't used then the warranty on Your Sierra will be void. Be careful when You go to the store to pick out Your oil and make sure that it is certified. You can even ask a store associate for help if You need it. What engine oil does is keep the engine lubricated and clean. If I were You, I'd check Your oil often so that You're not driving around and putting pressure on Your motor.
Natalie M.
August 29, 2019
The 2008 GMC Sierra engine requires oil meeting GM Standard GM6094M. The best oil for the 2008 GMC Sierra is the SAE 5W-30 oil. For areas of extreme cold, where the temperature falls below 20°F (29°C), it is recommended to use either an SAE 5W-30 synthetic oil or an SAE 0W-30 oil. Both provide easier cold starting and better protection for the engine at extremely low temperatures.
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