0w-20, or max. 5w-30, API SN / SN Plus, is the oil grade recommended for 1KR-FE, by none other than the OEM itself; Toyota (please see the latest owners / user manual for Japanese Vitz, Passo / Boon for further details and confirmation).
For best balance between pick, performance and fuel efficiency, you can use 5w-30, and with complete confidence and peace of mind (even if you live in Sibbi / Jackobabad).
Just prefer 100% fully synthetic or synthetic oil, instead of semi synthetic.