My wife drives a 19 Cherokee with the 3.2 V6. She has 112,000 on it so far. We bought it with 25k on the clock. I think the dealer we bought it from got it at a rental car company auction. The only engine problem we've had is the oil cooler started leaking down in the valley and onto the ground. My friend who is the service manager at a dealership said it's a fairly common problem. A few years ago, that part was back ordered from Mopar and they were forced to use some from a parts store. All of those vehicles came back in a year with leaky oil coolers again.

We had an issue with the gear box when it was still under warranty. It started leaking fluid. Not sure what the exact issue was but a part was replaced under warranty. I noticed some odd tire wear and the rear suspension bushings were shot and replaced at around 80k. Normally you have to replace the entire knuckle in the back on each side.(not cheap) The dealership found some aftermarket bushings that worked, so they replaced the bushings instead of replacing the entire knuckle.

I change the oil when the dash indicator shows around 30% life left. Letting it get down close to 0% would be putting way too many miles on an oil change.(a lot longer then I would be comfortable with)