If Toyota states in their maintenance book that you need to have the oil changed every 5000 miles, then you will void the warranty if you go 10,000 miles between oil changes. If the Oil Life Monitor says 5000 miles and Toyota says to follow the OLM, then change it every 5000 miles. And you can use regular old mineral oil if Toyota does not state that you need synthetic. Always believe the car builder first and foremost, especially during the warranty period.