Recommended oil? on 2009 Kia Spectra

I just purchased a 2009 Kia Spectra and was wondering what type of oil to use for the vehicle. Conventional? Synthetic? Any help appreciated. Thanks!

We always use synthetic if possible 5w-20 Mobil 1 available at Walmart in 5 quart jugs
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I need to know what oil to use also does new car warranty specify