In the Ecodiesel case you are following the manufacturer's oil change interval and in the gas case you are ignoring it and changing the oil twice as often for no apparent good technical reason. My 2018 Pacifica and my 2020 PEntastar Longhorn 4x4 both have a 10,000 mile recommended change interval. The two used oil analysis I have had done on the Pacifica both showed the oil in good shape at the 10,000 mile change interval. I only have about 5000 miles on the truck so haven't changed it yet but will do so at 10,000 miles and do a UOA test to see what it shows. I will do another one with the oil I will be using longterm when I do the second change. I am using Amsoil in the Pacifica but bought the new Shell Rotella full sythetic gas truck oil at a real bargain and will use that in the truck for the first 100,000 miles. It will be fun to see how the UOAs differ between the two.I am really curious why people think that the maintenance on the EcoD is so much more than a gasser. I change my EcoD oil and filter ~10K miles, 10.5 quarts. In gassers I would not go over 5K miles between oil changes, at least 6 quarts per oil change. So isn't that a complete wash as far as cost goes? I use Ecogard oil filters and have, so far, had no issues. Cost is $15 each, or less. However the Mopar filters are ~$35 dollars which isn't that much more since they go 10K miles. I do use the expensive Mopar fuel filters for the obvious reasons. So I only see the filters as a possible extra expenditure. Since I change my own oil and filters, there is no labor up charge on diesel or gasser. We all know that the engine has been problematic and I am taking that out of the maintenance equation because it is not every truck that has those issues, I am speaking to scheduled maintenance only. Please tell how I am seeing this wrong.
I use WIX filters on the PEntastars and they are less than $5 each if you get them at the annual sale some auto parts stores have or NapaGold with their sale are about the same.
In summary, follow the manufacturers recommendations in both cases and the Ecodiesel will cost at least twice what the gasser will cost if you look at oil cost (suitable full synthetic gas engine oil is usually cheaper than full synthetic diesel engine oil) , oil filter cost, fuel filter cost and air filter cost.
All the best,