Well, GPs run well on pretty much any oil. Anyway like matt said dark oil doesn’t mean its is bad or used up. I wll say this, unless your car has a known problem changing the oil every 2500-3000 miles is a little over kill. But it's your car, what ever makes you happy. I personally use Castrol GTX every 5000 miles, and use AC Delco filters. But honestly most any brand name oil or filters are about the same. Fram oil filters are built on the cheap side, and K&N filters are built heavy duty. I have run pretty much every filter out there, hard to say which ones are any better than the next one. Anyway for my dollar I’d recommend using the appropriate (either GTX, high mileage, or synthetic) 5W-30 Castrol oil and skip using any additives. And for filters AC Delco or Pure 1s.
