I put 0w-20 fully synthetic Honda oil it in my oriel x today at my first oil change at 5k, mechanic at dealership told me that most of the people are putting 5w-30 in Oriel and that is 800 cheaper than 0w-20 but I insisted on 0w-20 coz I knew the mindset of our people and their USTADGEE mechanics who are still convened to buy mehran, xli,gli over JDMs.
I remember a few year back people were afraid of buying an automatic transmission but now 8 out of ten prefers A/T so I decided to go with the time.
As far as I know and researched on it I found that there is a big misconception that a thicker oil can lubricate the engine better but now from last decade technology advancement is at full pace so no need to dip engine into a high density oil because now engines are smoother and oils are very advanced.
There is no big difference of atmospheric temp upper limits b/w both but difference is at the lower temp/start-up, upper limit of atmospheric temperature has nothing to do with it, operating temperature of engine is way above almost 100 degree Celsius for all outside temperature ranges so what about to care most is the cold start of engine because maximum damage occurs at the time when engine runs cold so 0w gives better protection to engine at start-up as compared to 5w, it spreads quickly and oil pump have to do less job for its circulation as it is advance technology so it can protect effectively with a thin layer which will also be helpful for engine to move freely whereas thicker oil will take more time to spread over engine and it will put more load on oil pump and engine moving parts and leave relatively smaller place in piston chamber which will lead it to power losses and will put more load on the seals, head gasket etc so it is better in all ways if we accept it logically.
I driven the car for 20kms after oil change and felt a lot of positive difference in my pick, sound and economy, it given me 10% more fuel economy for those 20kms at same road and same driving style.
Though all the plus i mentioned in favour of 0w-20 will be nominal and it doesn't means those who are using 5w-30 are ruining their engines but In my humble opinion all the plus are in favour of 0w-20 except the mindset which is major factor of its failure even when Honda itself recommended it.