If your vehicle is running absolutely fine on ZIC A+ 5w-20, and you are also comfortable and satisfied with it, then why switch brand / grade?
You are already getting excellent fuel efficiency from an 1800 cc car. What else is needed?
I would suggest to keep on using the same engine oil grade. At max, change the brand.
For filters, or anything, Parts Central PK all the way!
https://www.facebook.com/pg/PartsCentralPK/about/
And... Heartiest Congratulations on your purchase.

May it serve you long; mat it serve you well. Ameen. 