i have a 02 BMW 530 with 95K mi that has Castrol Syntec 5W-30 now. previous to this the car has had nothing other than BMW 5W-30 high-performance syn oil. My Indy (Taylor's in Pomona) just recently switched to putting Castrol Syntec 5W-30 in all customer cars that call for the BMW 5W-30 syn oil. i was concerned about that since the BMW oil meets the A1 spec and the Syntec 5W-30 only the A4 (if i remember right). i concluded that spec was just about long-life and decided to change this oil ofcourse at 5-7,500 miles (then to just put more Syntec 5W-30 in again). Now i'll be bringing in my own bottles of Syntec 0W-30 ( GC ) from now on. I was able to get 8 quarts of Green GC from local Auto Zones. Now it's just sitting in the garage. Should i put this stuff in now? there's about 2,500 miles on this oil. I thought i read somewhere it's not good to change syn oil so frequently.