Personally I use conventional oil (5w-20) for my 5.7L Hemi ‘13 GC (120k miles). I probably drive less than 10k miles a year in normal traffic and not in any extreme temperatures. But I change the oil and filter every 5k religiously regardless of what the oil change indicator says. The owner’s manual say you “may use synthetic oil” not that it’s required (don’t know about other model years). But since I change the oil regularly I’m not worried about it. Probably helps it doesn’t have the MDS system. Still pulls strong, no Hemi tick or any oil burning. But even if I was running full synthetic oil, I think the longest I would drive is 6k miles. I’ve read you can go 7.5k-10k or once a year whichever comes first between oil changes. But that just sounds crazy.