I usually use sopus or Castrol products but today I picked up the mobil 1 5w30. Wallyworld didn't have qsud in the 5w30 flavor. It was 22 dollars for a 5qt jug so it was only one dollar more then qsud so why not. Now ive heard that using m1 can show more iron in the uoas but im not sure about that. Anyone hear use m1.