I think the iron is valve train wear and ring/cylinder wear, since these are the main ferrous materials that see high pressures and oil temps....
For example, crankshaft journals are much harder than bearing overlays, so for the most part, it's the bearings that wear and not the iron from the crank
Tooslick
For example, crankshaft journals are much harder than bearing overlays, so for the most part, it's the bearings that wear and not the iron from the crank
Tooslick