Yes Bro, you are Right.
0w-20 would give best fuel consumption and peak performance, but it should never do this at the cost of Engine.
Depending on the weather / environmental conditions here; aesa na ho k engine toll laina shuru Kar dey 
due to minimum lubricantion between different engine parts (since it's the thinnest oil I have known yet).
Some say it's best suited for Winters here.
Some have been using it throughout the year without any issues.
Like everyone else, I would also want to get peak performance and best fuel efficiency from my engine, jitna thin, utni hi behtar fuel consumption and achi performance! but, main kabhi nai chahoon ga k 2-3 saal k baad mujhay engine overhaul ya replace karwana paray; if I use 0w-20 throughout the year.
And main tajurba b nai karna chahta.
Ub Banda Kya Karay?
5w-30 p to issue hi koi nai.
Issue 0w-20 and 5w-20 per Hai.
Since many years, ZIC A+ 5w-20 fully Synthetic motor oil has always been recommended by mechanics for Vitz and has been in use.
I would be happy if someone having experience with 5w-20 fully Synthetic (be it ZIC A+, Shell, etc.) for more than 2-3 years could share his experience and shed some light that whether it's recommended or not?
Agar 5w-20 Ok Hai, then 0w-20 b Ok Hai. Since just cold start ka faraq Hai, otherwise, I think their viscosity parameters are the same.
