I love the "v8s have to be maintained religiously for you to buy one" answer. Any engine has to be maintained religiously, even a 4.0. The mentality that you can treat it like **** just because its a 4.0 is stupid IMO. The 4.7 is a great engine and is much more suited for the wj. Yes the 4.0 is a great engine and lasts foarever, but is underpowered for The wj. You want fun, reliability and power when you need it, get the v8. You want underpowered and reliable get the 4.0. Parts aren't any more expensive for the 4.7 and you get the same gas mileage. I personally would never get a 4.0 in a wj when the 4.7 is an option, couldnt you tell? Drive one with a v8 and you won't even consider the 4.0.
2000 WJ - Quaker State Full Conventional 5-30, Fram Oil Filter