Toyota sell the 2ZR and 1KR across the globe - they have the same oil 0W20 oil spec for anyplace on earth. UAE is not special no matter how much gulf news you read.
Please stop the typical Pakistani rants of ego and let go, Its you who started a discussion claiming bases of academia, but I have yet to find a single word that can support your original statement academically.
I thought this would be a nice eye-opening discussion, but all I see is the same "thick oil myth" from the early 20th century.
btw - for tropical package delivery or severe duty package vehicles (police cars etc) - look at their build sheet (code sheet), you will understand what they install extra to combat extra heat. They do not rely on thicker oil (which is counter productive anyway)
e.g. the most severe heat package Ive seen is on BMW, Benz and Audi who install a whole extra engine coolant radiator and have a larger capacity oil cooler too.
similarly on cold requirements I have seen different PSF being used, e.g. hyundai changed the original fill of ATF based power steering oil in the genesis to CHF202 (its a 310 VI hydraulic oil)
I have yet to see a modern manufacturer claim to use a heavy engine oil in tropical area.
