Hello Prius mates: I have three brief questions: 1) I bought a 2010 Prius 3G 6 months ago, it only has 1k miles. Should I change the oil? Or should I wait to have 5k? 2) I don't know what kind of oil the dealer used to fill it. So, in case I have to add oil, what kind of oil should I use? I mean can I add synthetic oil to whatever oil these guys used. 3) Can I change the oil myself and keep the Toyota warranty, or to keep it, it HAVE TO be done by a dealership. Thanks in advance.