Just a point of note: Any oil that has an SM rating or CJ rating on the bottle has only 800 ppm of zinc regardless of what the marketeers have put on the bottle. Valvoline for example makes two types of VR1 one with the SM rating and only has 800 ppm and the other that has no sevice rating and does contain more. The VR1 you see on the shelf at your Local chain store is the SM rated stuff.
