I have the same engine with 173k on it; I've used a variety of dino oils but nothing less then Penzoil, Mobil 5000 or Castrol GTX or Castrol HighMilage and all 5w-20; and the result is the same if not even better;
the engine and overall the car is in solid shape though I changed oil pretty much each time around 3k; in my case testimony to maintaining clean engine is an interval rather to a brand name