There is a post in the used oil analysis section about synthetic Valvoline being used for about 4800 miles in a vehicle. Remember, this is synthetic, not conventional. Although people said that it looked alright, there were statements like the oil had come to the end of its useful life, recommendations about using Mobil 1, etc. Now, this synthetic oil had gone only about 4800 miles. Some people at this web site use Mobil 1, Schaeffer's Oil, Redline, and Amsoil for 8000 miles! If somebody wants to maintain loyalty to a given brand, like Valvoline, that is fine with me. But I would use the Mobil 1, Schaeffer's Oil, Redline, or Amsoil myself. In the one post I mentioned earlier about conventional Valvoline in the virgin oil sample section, there were statements to the effect that the oil would be good for only about 2000 miles. I don't know about you, but I go 3000 miles with conventional oil (like Chevron). From what I have been able to find out at this web site, conventional Chevron should be acceptable for 4000-5000 miles. A person should be able to go 5000 or more miles easily with Schaeffer's Oil, and the partly synthetic Schaeffer's Oil is about 3 bucks, compared to 4 or 5 bucks a quart for Mobil 1 and Valvoline synthetic.