In the sonata manual book, it has a normal condition timeline for oil change intervals and a severe condition oil change intervals. I live in Texas DFW and it gets oven like here too. The dealer said in Texas, we should use the severe condition oil change intervals which is more often than normal condition to keep the engine from broken down oil. With Hyundai warranty, I'd be scared using any other oil. But that's me. Since we got the sonata, we've always taking it to the dealer for every thing like oil change, alignment and whatnots. But I am sure others here have already used their own preference in oil and gotten same results as dealer oil. And you are right, seems like most people here are always in snow lol
I've never heard of an oil keeping the engine temps lower. I've heard of radiator fluid additive to keep engine cooler. I don't know if those oil products you are talking about are going to be friendly to the turbo. I don't know much about turbo and if they are picky about certain oils or not .