new technology engines run on low viscosity for best fuel efficiency .. if you see all JDMs manuals even back from 2012 like mine recommend 0w20 upto 40C temp . they run best on it.
What ever is written in manual is the best thing for your car .. not these mechanics of pakistan who have been working and on and only have experience of engines which are 40 year old technologies.
company walay bewaqoof to nhi ke manual main itni bari ghalti kar dain
... use 0w20 for best performance and fuel efficiency brother. my honest brotherly mashwara