What brand of engine oil do you use?

[Ry_Tower]

Using Petron's REV-X PREMIUM MULTI-GRADE (TREKKER) for my 2007 Starex CRDI. REV-X PREMIUM MULTI-GRADE (TREKKER) | Petron

And the PETRON ULTRON PREMIUM MULTI-GRADE (TOURING) for my 2009 Picanto. PETRON ULTRON PREMIUM MULTI-GRADE (TOURING) | Petron

Should I be switching to something else?

If you are happy with them, then don't. They are good oils.