I was at 1400 miles, I did my first service at 600 with regular dino oil and it was fine until now. I decided to change it at 1400 with the mobil 1 racing 10w-40 and now it shifts like total crap. I keep missing 2nd and hitting neutral and sometimes have to jam it into gear, i'm really fixin to dump this "good" oil and go back to old dino oil