First, I am not coming to any conclusions based on data of unknown (to me) origin. But I have looked at a data set that has left me with a question. Background: In another thread, "1sttruck" is attempting to use a data set (origin unknown to me) to derive conclusions about viscosity and wear. I collect, analyse, and publish data for a living. So, I thought I would download the data set and "have a look". Excluding the obvious issues with unknown confounding parameters, the first thing that I noticed is that the Fe and Al numbers are not a good fit to a model where wear of these metals is linear with miles traveled. The transformation of the data as "miles per unit metal" is therefore not valid. Observation: However, the Fe and Al are highly correlated with each other. It is my impression that Fe and Al would rarely be found as opposing, moving surfaces. So, what factors would make Fe and Al climb together? I am left hypothesizing that maybe corrosion (however small) is the main source of these metals in used oil. I have found several references for marine oil usage that suggest that corrosing is the main source of "wear" in those applications (maybe as high as 90%). Does anyone know if corrosion could be the main source of wear in the average auto? If so, then lubrication would not be the current weakness in oil. Instead, the current weakness would be inhibition of corrosion. This situation would change the way that I think about oil. Any thoughts? Facts? Feel free to blast me if I am way off base. I would think that a good tribologist would have a well established answer for this issue.