My understanding is that for the great majority of daily drivers, conventional 10w30 for the better part of the year, 20w20 conventional (monograde 20) for late autumn, winter, spring. To me, this is the ideal after having read BITOG, and also in part based on my experiences.
Monogrades are really preferable (if the climate is moderate) especially because they strongly resist fuel dilution, but on the other hand it is definitely not advisable to use 30 and 40 grades in variable valve timing type engines, such as yours.
5W30 sheared too rapidly 20 years ago, but in whatever kind of motor oil, 5W30 grade in general is better than ever, many improvements. Nevertheless, 5W30 continues to shear earlier during OCI than 10W30; speaking anecdotally through BITOG browsings, the only 5W30 I personally find trustworthy are old Pennzoil Platinum 5w30 rated at A1/B1 and A5/B5 (the one without the Dexos1 label) and old Pennzoil Ultra 5W30 (this one may be a real synthetic as it contains GTL and may also contain PAO and/or esters) and dino Mobil Super 5000, and maybe the old discontinued Mobil Clean 5000 and 7500 SM GF-4. I could also name Kendall and Chevron Supreme oils, but that's practically speaking not over the counter in much of the U.S., so I exclude those from the 5W30 Pantheon; actually Chevron is more over the counter than Kendall, but because of the watered down Havoline SN (which I shun), let me also exclude Chevron which btw is more or less the same as Pennzoil conventional, but it seems (this is a totally subjective statement) to me that Chevron Supreme is somewhat better and longer lasting than Pennzoil conventional. Btw, I actually like Quaker State Advanced Durability dino more than Pennzoil conventional, my opinion. Mobil 1 5W30 bottles in the USA used to carry the label of "New Vehicle Formula", for example, 10 years ago, and continue to do so when being sold in New Zealand and Australia, to this day.
A DI engine being subject to constant fuel dilution, and for other reasons such as intake valve deposits of oil oxidation, once properly broken in, either 100% 10W30 or a blend of 5W30 and 10W30 (for winter operation, because it is not really feasible to buy monograde 20 oils) dino, speaking of such widely available conventionals as the low-to-mid SAPS Valvoline conventional, Mobil Super 5000, Quaker State Advanced Durability ( Quaker State Conventional), Motorcraft Syn Blend.
Through BITOG one learns that frequent oil changes in one sense is not good, because it is at the early part of OCI that the most wear occur because of fresh detergents competing for metal surfaces with fresh ZDDP molecules. But if you are doing a very moderate around 4K OCI, this fear (based on scientific reality) is a bit exaggerated. If you run especially either Valvoline conventional or Mobil Super 5000, because their starting TBN are rather low (no problem, they also contain the very beneficial and low cost sodium additive), especially Valvoline conventional being pretty low in TBN, detergent molecules competing with ZDDP molecules is minimized. You could use Valvoline 5w30 conventional year round in your application between 3.5K to 4.5K, and your engine will run very well with lower wear numbers, changing the oil filter every other OCI (because the motor has already been broken in), so run it 7K to 8K per oil filter.
You utilized from the beginning Pennzoil Platinum and Quaker State Ultimate Durability synthetics, is that right?
If so, it turns out you did no harm or very little if any, by doing so, because those two are not really synthetic oil but more like super charged conventionals. Pennzoil Platinum and Quaker State Ultimate Durability are neither synthetic nor dino, because performance wise they overlap both categories. Chemically, they are dino. For all practical purposes, Pennzoil Platinum and Quaker State Ultimate Durability and WPP produced synthetics are pseudo synthetics (Group III). Which is to say, that kind of motor oil is the closest thing to one size fits all approach. Nevertheless, because such oils have moderately high starting TBN, for DI applications Valvoline conventional and Mobil Super 5000 are closer to the ideal.