I was just asking the question. This oil sludge problem is popping up in lots of places. Some dealers/manufacturers deny it and say the owner is not changing the oil, but does that explain all these episodes? My neighbor had a 4.7 Durango and the engine failed long before it should have. He was told by the dealer that all his receipts were 'faked', so he took them to court and won a judgement for the whole job. The dealer made no effort to work out a solution leading up to the court date.
This oil sludge problem has got to be a lot more complicated that it appears. There must be sludged up engines that got screwed up in more than one way. They can't all be the owner's fault, can they? He sold the Durango the week he got it back with the new engine and has purchased a Toyota Sequoia (spelling?). He bought the vehicle based on a lot of research. He wanted a bullet proof V8, so he settled for a much less powerful engine than he could have had, but one with a good reputation, and no stories about oil sludge.... In fact he ended up with another 4.7 engine, just a different one.
By the way, the Durango driver used 5w-30 dyno oil, Castrol, the right spec and weight and changed it every 5-6k miles. He did do a lot of stop and go driving and just running around doing short trips. The Durango was the vehicle everyone in his household wanted to drive, with 3 kids and two dogs. They lived less than two miles from the boat dock and a mile from the horse corral and a mile to work. I think all the short trip running around may have been a big part of the problem. With his new Toyota I convinced him to use Mobil 1 0w-30 and keep the 5-6k change interval because of their driving habits.
