Did you read the owner’s manual?
Mine is 2008 5.7L Hemi. This one calls for traditional oil, but the owner’s manual specifically states synthetic can be used.
Mine had 13,000 miles when I bought it used and since owners manual says it’s acceptable I have been running Mobil 1 or Valvoline full synthetic ever since I got it. Now it has 260,000 miles on it, and try to keep the change interval to every 4,000 miles or less. An engine can never be too clean, and these Hemis do not have adequate pcv systems.
Biggest thing for warranties is you must save receipts showing the oil filter and oil suggested for the vehicle, and the purchases must add up to the mileage, so going 10,000 on a synthetic oil chance won’t add up. A friend actually takes pictures of the odometer and of the oil being poured in to go along with the receipts.
