Assalam-O-Alaikum Brother.
Hope you are good.
I am also using the same car and bought it few months ago. 5W-30 is good oil if meeting all the following requirements. API SN / SN Plus, Fully Synthetic. My advice is to go for 0w-20 it will give you good fuel average Inshallah. Following are the good brands.
1) Total 5w-30 future series (Normal price range)
2) AMSOIL(costly)
3) ENEOS Sustina(costly)
4) KIXX(costly)
Make sure Oil is original. The oil capacity for 3rd Generation vitz is 2.8 liter. Don't pour more than 2.8 not even 3.
Following is the periodic maintenance of your car that will make it healthy.
- Change air filter every 10k km.
- Change CVT oil every 50k km. Use Toyota CVT oil around 3L capacity.
- Change brake pads front and rear every 50k km use only Toyota parts or aisin one. No local brand.
- Change spark plugs at 100k km use iridium plugs only.
- Check coolant every 50k km use Toyota LLC around 3-3.5L or caltex coolant.
- Clean catayatic converter only when pick decreases and fuel economy is bad and car is really struggling otherwise don't break it ever.
- Clean the throttle body if its get dirty.