The car came with 5W-30 motor oil. You can absolutely run 5W-20, it'll perform as well as 5W-30 and offer cold start benefits.
5w20 and 5w30 have no differences in cold start benefits as the are both a 5w on the cold side. Best thing to do when deciding on oil, is run what the manufacturer designed it to use. Many times the correct grade of oil will be on the oil filler cap or in the owner's manual. I would under no circumstances use a lower grade oil than what is recommended (lower meaning 5w20 versus 5w30).
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