I've run Havoline 10w30 for the last 100,000 miles and no problems at all. I used synthetic up until about I reached 90,000 miles. So I guess, I've been on nomral oil for the last 53,000 miles.
Some swear by synthetic continuously, but I've had no issues. My engine hasn't been cracked open yet and it still runs very strong. If you change your oil and oil filter regularly, like every 3,000 miles, you'll be fine. Good name brands are Havoline, Mobil1, Penzoil, Valvoline, and a few others.
I've stuck with Havoline for oil, oil filter, coolant, and tranny fluid. As long as things are clean and serviced regularly, you'll be in good shape for a long time.
Original owner ran Amsoil changed every 5K, I think they claim it's good for 1year or 25K. I put amsoil in when I stored it and it still looks good (checked today)
With that kind of mileage I'd watch it though some synthetics have strong detergents that try to clean the engine out, they can knock out gaskets and start leaks, personally I'd run whatever you've been running, if ain't broke don't fix it, not enough people take that advice.