Originally Posted by paoester
The fear is that 0w20 oils are using too much VII, and, if you don't need a 0w winter oil, then skip the extra VII so your pistons are cleaner. Also the long term shear stability is in question since 0w oils use thinner base oils in general.
That logic will almost work. Not quite though. ....All things being equal with base oil quality, it does make sense. Often they are not equal.
Got any hard data to back up your "fear"? Even better, do you have anything other than anecdotal "proof" that 0W20s are not sufficient in engines that the manufacturers specify this oil for?
Originally Posted by paoester
Like already said above, some 0w20 oils are made with more PAO to get a better viscosity index and low temperature flow properties without using too much VII plastic-based chemicals.
Again, where's the proof that 0W20s are made with "more" PAO? There are only a handful to start with that use PAO (the majority use Group III or GTL from evidence presented so far), and the oils that do use PAO likely haven't ever changed their original formula for the amount of PAO.
Originally Posted by paoester
If "out the wazoo" engine testing is not enough for you, then go up in performance specs to VW 508 (or LL-17FE+ or 229.71) 0w20 oil for more engine testing
proof to make sure your oil is better.
Do you have any "out the wazoo" proof to show that just because an oil meets VW508/LL-17FE+/229.71 specs that it is applicable to a Jeep Grand Cherokee and that FCA will warranty the OP's engine if he suffers a failure? This is what I found on OP's engine:
Originally Posted by JGC OM
Engine Oil - 3.6L Engine
We recommend you use API Certified SAE 0W-20 Engine
Oil, meeting the requirements of FCA Material Standard
MS-6395 such as Mopar, Pennzoil, and Shell Helix. Refer to
your engine oil filler cap for correct SAE grade.
So, what I read as FACT is: use 0W-20 oil in the latest and greatest API specification (currently SN+) that ALSO meets MS-6395 requirements. Curiously, paoester, none of your recommendations are supported by the manufacturer's requirements...