I have a 2006 toyota vitz thats done 190K+ kilometers.

According to online sources, the 1 KR FE engine in my car should be filled with 5w30 grade oil.

However my friend whos very into cars advised me to get a higher grade due to the high mileage.

Should I? And if so, is there some foolproof chart?

Exactly what grade oil should I get?