Quakerstate is one of the worst brands of oil out today. If you want one of the best bought oils on the shelf, get Penzoil Platinum. So far on all the tests from the labs, it has done much better than all of the competitors other than Amsoil. Mobil 1 is way down on the list now since they reformulated their oil.
If you want sound advice, I suggest go to
www.bobistheoilguy.com and discuss the oils there.