04 3.5 engine oil specs

I'm new to this forum, so please be patient. I recently bought a used 04 Santa Fe LX with 3.5 engine. It has 85,000 miles on it and I need to do an oil change. The owner's manual shows 20w50 for our hot desert climate zone but I checked with a couple of Hyundai dealerships and they both said they use 10w20 oil. Anybody have any insights as to an appropriate oil viscosity where the ambient temperature can easily exceed 115 F?

In my '01 Santa Fe and the wife's '07 Tucson, both with 2.7 liter engines, I use Mobil 1 10W-30. Even though I'm not in the desert Southwest, it gets pretty hot in Alabama in the summer and we use the air conditioner a lot. I suggest using 10W-30 or 10W-40, but I have to also suggest using a Hyundai oil filter, too. There are numerous posts here and in other message boards about engine noise with an aftermarket filter that quiets down when the OEM filter is used. I can back that up since it also happened with my Santa Fe.

Personally, I will NEVER, EVER again use a Fram filter on any car as I used to. After seeing how they are constructed inside, I will not take a chance on catastrophic engine damage caused by filter failure. Just my $0.02 worth.