My daughter's WJ has the 4.0 with around 225k miles on it. I'm pretty certain that it's got one or more cracked pistons as it's rattling like crazy. I'm 99% sure it's not timing chain noise or a collapsed lifter.
Not really many miles as this is a second car. It got more miles per year when newer. 2007 Grand Cherokee 4.7 V8 now with 110,000 miles. No oil use, no transmission problems. Needed a radiator replaced. Still runs great but it is a gas hog.