arod
I think the catch can "possibly can" be important in keeping your oil a little cleaner. Whatever you burn ends up in your exhaust and your oil, so perhaps not sending that garbage bac=k through your engine might keep it cleaner.
For the 6.4 I only recommend Ultra at this time, it is the only one that meets the spec that I know of. When an oil says "meets or exceeds" I believe that is all you need, but from what I've seen no oil company other then penzoil has met that spec. redline has a 0w40 but I wouldn't use it in an SRT until they said "meets and exceeds" that new srt spec. I'm pretty sure Redline and most other oils will meet that spec, but until they advertise that they do, you kinda should use what does. Redline 0w40 meets MS-10725 the older Chrysler spec and probably meets the new spec as well, but they don't say it yet.
So any oil worth running in your car/truck says what specs it satisfies. Look up your oil and look for spec MS 12633. Until it shows up your better off using Ultra. It seams like Ram might be monkeying around with that spec and the oil industry. Maybe penzoil is giving them some payola or something. So an example
is this go down to specs and approvals, if you look at the specs for Mobil 1 0w40, this spec is not there. Means they have NOT tested for that spec yet, not that is doesn't meet it.
From my information, most of the UOA's have been coming up with high numbers with the 5w20's in any Hemi, especially copper. Just like everyone else here, I'm still trying to find a solution if it exists. It wouldn't matter though, the oil is still good for a year as mine still looked brand new on paper, there are just higher wear numbers. So changing your oil early wouldn't accomplish anything, your engine will still be wearing at a high rate with used or new oil. It is a product of hemi versus 5w20, and so far I do not have an answer. I encourage you to look up "uoa 5w20 and hemi" and read up. I also encourage you to look up 5w20 and wear.