They are just sales men and they are doing whatever they are told to do to sell the oil bottles. As a fun, next time you meet him then ask couple of simple questions like what minimum rated API oil i can use in my car ?
The recommended motor oil for 2017 City is 5w-30 or alternatively 10w-30
Just stick to these oils only.
Secondly, there are too many options available in the market as compared the contents, grades, certifications, classifications, etc. and it literally confuses everyone to choose the right type of oil. Because if 5w-30 is fully synthetic, then its life is longer than other 5w-30 who are either partially synthetic or semi synthetic.
I remember like 15 years ago when I read a motor oil broacher of liqui moly and at that time they had 5 types of 5w-30 oils. One regular usage, one premium, one partially synthetic, one fully synthetic, etc. And I was like how difficult its for someone to choose the right oil !!!!