Never trusted any of that stuff. I use Mobil 1 and change it every 3500 miles. Still fairly gold when it comes out and I am sure I could run it longer but I love my car and its cheap. Car has 100K on it now and dont leak a drop and looking down the oil fill hole I can see my head is very clean inside. In a couple weeks I am swapping the valve covers so I will get to really inspect it.
My 96 Cobra spent its whole life only getting Mobil1 or Valvoline full synthetic and at 120K I removed its valve cover and its heads were perfectly clean with NO sludge or discoloring from cooked on oil.