My jeep manual for the v8 says something very similar. It also says that it recommends the 5w-20. No stipulation for mineral,or synthtetic.
The 5w-20 is only mandated for the HEMI. Mineral or synthetic is not really mentioned.
I do know of many people including myself who choose to use whatever weight/grade we desire,even the HEMI users have reported the 0w-30 100% synthetics work fine.
It would seem there is some perception that putting 5w-30 premium synthetic/amsoil in an engine is going to cause the engine to blow up,or develope wear issues because the mfg 'recommends 5w-20/dino oil,thus voiding the warranty............that is impossible.......never happened..........and is against the law.
You see folks,I have a family that used to be in the car business myself.
I was a sun-snap on rep,sister was a chrysler rep/district manager,and we never ever saw or heard of any warranty issues because someone put better/different oil then the manual recomended,such as amsoil,lucas,stp,etc,and got denied.
The issues I saw were cars where the owner forgot/refused to change the factory oil,and the engine blew at 20k with the factory stamped oil filter still on the "leased" car.
I suppose if a customer had straight 50 mineral oil installed in Maine during winter, and blew the cam out......that would be the exception and not very hard to catch.
If you are that 'paranoid',drain whatever oil you have in the pan,and install what the manual 'recommends'...before you go in to have your car serviced for, knocking,tapping,ticking,smoking,piston slapping,chain slapping clunker repaired,from all the damage that a premium syntheic 0w-30 caused.(lol)
However,everthing else,is strickly academic.
A little bit of an explanation to read