Neither dealer I talked to could tell me when Chrysler started "requiring" the 3.6 to use nothing but 0w20. My 300 is a 2016 & the Dodge dealer does all the oil changes & uses semi-syn 5w20. So far, no rocker arm issues, even though I get clatter which is quite audible when the engine is cold - takes about 10 minutes of driving before it subsides. I've had two dealers look for this & they come back with "no rocker arm issues" each time. Personally, looking at repair videos & listening to what the Chrysler techs are saying, I don't see how these rocker assemblies can remain trouble-free in under 100,000 miles. Same thing with the driveshaft center support bearings on the 300's & Chargers. THEY ARE ALL GOING TO FAIL PREMATURELY! If you are driving a late model Charger or 300 & you are starting to feel a driveline vibration at highway speeds, it's the center support bearing! It's a 2-grand repair if you are out of warranty.

Rant off.