I may be out of my league here but I’ll give you my understanding to the logic behind this. When you create more power in a car- that will also create more heat. The more heat you have the faster the oil will breakdown. So going to 5w40 and a little thicker will in theory protect your engine and turbos a little longer than the 5w30 would. So why you see the companies that sell added power recommending 5w40. They want to have more protection once you add the extra fun! Obviously good oil and change intervals probably trumps all anyways! But those are my two pennies. Side note: 2018 Stinger actually has 5w30 and 5w40 recommended in the owners manual. For some reason 2019 and up the manual stopped showing 5w40. (My guess is fuel mileage)