I notice that Quaker State and Supertech are neck and neck in this discussion. People of good will will place either oil on top, and relegate the other to the second position. I also note (again) that folks rightly equate Kirkland with Supertech. Personally, my right brain will allow that these two (three) oils are excellent and equivalent, and that the Valvoline product, though fine, is correctly in last place. My left brain, though, has me giving the nod to the Quaker State brand, which has been delivering lubrication since 1921.