What happens if the car dealer made a mistake on the contract?

I’ve had my car for five years now and it’s always run smoothly. Recently, it’s started to make a strange noise—kind of like a ticking. What might cause this?

I bought a used 2004 Saturn Ion for $500. I don’t drive it all that much, but it seems like it burns oil quickly. Since I only spent $500, I’m not going to fix the cause of the problem; I’m just going to change the oil more frequently—what oil type do I need for a 2004 Saturn Ion?

I got into an accident shortly after getting my new car and would like to file a diminished value claim. What do I need to know and do?