So I reached 3000 miles on my 2010 370z and finally decided to change out the factory oil. The oil was really dark. I put in 5 quarts of Penziol Ultra Full Synthetic. I noticed that the car felt smoother and idled quieter. Before, I could feel the shifter vibrating in my hands, but now the car just felt right. I was not expecting so much difference from just an oil change.