2002 dodge 4.7 Engine sludge
I had a 03 durango and it did the same thing. I've heard of sludge problems trashing the motors, but most of the forums suggest if you stay on top of the oil changes it wont blow up. Seems like most of the "junk 4.7" claims are from non-automotive types that think you can go several thousand miles over on an oil change. I ran mobil 1 and it reduced the sludge you are describing in my case. For a while i took the baffle out of the oil fill thinger and it got even worse, so don't do that. I simply cleaned it whenever I checked of changed the oil. fwiw, Im halfassed looking for another Durango and I definitely prefer a 4.7 over a 5.2/5.9 due to better mpg, power, and transmission.