My first oil change was at 1000 miles (break in with 5w-30 bulk Dino oil). My next change was at 2500 miles, figuring to get rid of the last break -in residuals, that may be in the crank case. Also I was getting increasingly nervous about running my engine on 5w-30 dino juice, as much as I like to rev it. What to refill, was the question? Well, I felt my 2 perennial favorites of oil for NA engines, Mobil1 0w-40 and german castrol 0w30 (runs thick at operating tempos for a 30 weight), Might be tooo thick at operatings temps for this real new and tight engine. usually I like thicker oils for the HT/HS, but I went with Mobil1 10w-30 which is about nine and a half centistokes at 100 degree C, if memory serves. Also M1 is VII's free in the 10w-30,but not in the 0w-30 or 5w-30 versions. Even tho winter is coming up , living in kentucky the 10w-30 will be plenty start-up capable and the 5w and 0w- will be unneccessary. So now I am enjoying VII free, Mobil 1 10w-30, Yayy!.. As hard as this car was driven lately, I felt a change was neccessary, also it gives me piece of mind to have a group IV oil in my brand new VQ35. I know your not supposed to switch to syn early says conventional wisdom, which is usually a good starting point. For this reason I didnt put in syn on my first change. But many other highly modern engines have M1 as factory fill. So how harmful can an early syn switch be? Amnyway i did it and feel good about it. Fred..