How do I go about filing a claim in small claims court against my car dealership?

I took the car for a transmission repair. Everything went well because it was under warranty. Then later, they told me my brakes had been contaminated with engine oil and that I will need to repair the whole brake system. The problem is the only place I would take my car for repair is the Chevrolet dealership. And, I already took my car in for repair six months ago, to change my brake pads at a different Chevrolet dealer. They are still a certified Chevrolet dealer and they have all my repairs on file. I do not know which dealer to send to small claims court? I do not know if the first dealer contaminated it or the one that fixed my transmission.