oil viscosity in 2009 yaris

[Bluevitz-rs]

In hotter weather it is ok to use 10W30. The oil just remains a little thinker when cold. And service interval has more to do with how you drive your car than a set number.

If all you do is short trips I'd recommend 6000-8000km with full synthetic and slightly less with regular oil. If most of your driving is long trips then you can stretch it out longer to the recommended service interval. Don't worry about the oil being more than a year old though if you don't drive that much.