I've already searched, I'm sure its there somewhere, but I didn't find it. Got the car with 6k miles on it, the dealer didn't have the manual so I don't know how often I'm going to be adding oil. How often should I be adding?

Sorry if its a repost :D

 

The rule of thumb is to check the oil level every second fill-up at the gas station.

That might seem surprising to people unfamiliar with this type of engine, but it burns a certain amount of oil in its regular operations.