[cashflyer]

The top 4 items on the chart are the API specified zinc and phosoporus content. It applies to any oil that bears that specification on the label. Manufacturers have a certain abount of leaneancy on the specified percentage to allow for manufacturing tolerances.

Oil for different purposes receive different specifications on their additive packages. All API ratings that start with an S are for gasoline engines. API ratings beginning with a C are for diesel engines. That's why the Shell Rotella can have higher legels of ZPh - because it is for a different purpose. The manufacturers say that their oil is tested for the purpose that they mark the oil for, and that you should not run diesel oil in cars, or car oil in bikes, etc. Some of this has to do with things like catalytic converter damage. And some of it has to do with marketing, IMO.