Heres my opinion...The synthetic oil thread is ALL vooooo doooo B.S.
When the FCA engineers who did all the testing on the 6.4 engine say that synthetic oil is NOT required and the engine will run fine on 5w30 dino oil, that's good enough for me...Heres a cut n paste of one of my post in another thread regarding why/how I base my opinion on this subject...
Thought process is based on these real world factors
Ive owned 14-3500 series H.D. trucks so far in my lifetime...Well over 1,350,000 miles combined on all those trucks...Other that the diesels, which I ran 15w40, the gassers, 5.7...6.0...7.4...8.1... all got the cheapest **** oil I could put in them...O.C.I. was ALWAYS around the 4-4.5k mileage, also included a filter change everytime....NEVER any internal engine issues EVER...All these trucks were severe duty, used daily thru out their lifecycle...I just don't buy into the voooo doooo that other 6.4 owners do, especially that my O.C.I. on this RAM will be at 5k intervals...Search the internet for the video that has the 2 FCA engineers stating that they did all the testing of the 6.4 motor with a 30wt oil in it.......Lol