Chrysler/Dodge 2.7 reliability?

I have rebuilt a 2.7L and am wondering how many of you (owning one) have trouble out of them when actually changing the oil with in 3000 miles i know Chrysler originally said 6000 but that's far too long for a gasoline engine IMHO. i have added an oil cooler to mine as an added precaution but I'm curious as to the reliability of the engine when properly maintained. And has anybody noticed a difference between using synthetic and standard motor oil in them?