I have a 2008 Toyota Prius.
I've looked at the manuals:
Neither mentions synthetic oil at all.
The Scheduled Maintenance Guide recommends changing oil and the filter every 5K miles but is probably talking about standard dinosaur oil.
These 3 sites recommend 10k but don't mention Prius in particular (or hybrids), so I'm hesitant to blindly follow them because I don't know if that makes a difference:
- https://shop.advanceautoparts.com/r/advice/car-maintenance/synthetic-oil-change-interval says "The special synthetic oil used for Toyota and Jaguar vehicles has been approved for change intervals of 10,000 and 15,000 miles respectively" .
- https://www.chicagotribune.com/classified/automotive/sc-changing-oil-autos-0519-20160516-story.html says "Toyota says if you use full synthetic oil, it's a 10,000-mile oil change interval."
- https://www.edmunds.com/car-care/stop-changing-your-oil.html says "Toyota has been shifting its fleet to 10,000-mile oil change intervals using synthetic oil."
https://www.toyotaofsantabarbara.com/prius-recommended-maintenance-oil-change.htm says "Some model year Prius may have Synthetic Oil and only require an oil and filter change every 10,000 miles or 12 months." (No other details.)
https://priuschat.com/threads/how-often-do-you-change-your-oil.84594/ has a bunch of anecdotes with no official documented recommendation.