I use Motorcraft Full Synthetic 5W-30 in the Mustang, and have tried to keep it an All Ford Product. Since the selling dealer uses Valvoline Products, that I do not want in my Mustang, (1) oil change that lasted 400 miles or less, I have gone to another Ford dealer that uses Motorcraft. Especially after the manager, of the selling dealer, kept denying that his crew put in VWB in the car. The invoice showed Durablend, however, the number indicated bulk 5W-30 VWB from a 55 gallon drum. The manager admitted that he lied to me and said that the next oil change would be a full synthetic for free, I did not take him up on his offer. I have since moved and have contacted another Ford dealer and they use Motorcraft 5W-30 Full Synthetic or Mobil One 5W-30 Full Synthetic. I am thinking of using Mobil One in the Mustang next time. As I wrote before, I would like for the Mustang to remain with Motorcraft Products, however, I think that Mobil One would be the best for all of my vehicles.