How do you know that 15 ppm of iron in the oil is detrimental to the engine? It might be more appropriate to look at the elements at the bottom of the list like molybdenum, calcium, boron, magnesium, phosphorus, and zinc. Except for magnesium, they are all lower than the universal average for those elements. That might indicate that the additives are lower than normal, if only a little low. That may mean your oil change interval is acceptable, or you might want to decrease it to one year and see how that affects the elemental analysis if you are conservative.