Bhai i know all this theory and is available on google across multiple sites. I myself used 5w-30 and is still using same. For next oil change, i m planning to goto 5w-50.
All theories fail against practical experiences. 2zrfe performs exceptionally well on 5w-50. I m talking about real world experience interms of mileage. Every single car being driven on 5w-50 gives better mileage and very smooth drive. That said, mine is also fine and there are no issues at 5w-30. Toyota suggests both oils are per manual. Idemitsu is blending 5w-50 for imc and many senior friends use mobil1 5w-50, getting awesome mileage as well.
Manual doesn’t say dont use 50w, and somehow 5w-50 suits this engine very well. I also used taglon in 2018 when i bought car but then switched to 5w-30. That being said, there was nothing wrong even at that time. Every single grande running on 5w-50 is super smooth and fuel efficient alongside reduced engine noise.