In answer about Phosphorus that and Zinc are two additivs that help to lubricate engine parts in shear ie Cam and flat followers which are comming less used in the modern roller tappet auto/truck engines, however Cummins still have flat tappet design as do most of the avaition engines of the past 50 years and IMO Zinc and phosphorus are necessary and both T4 and T6 Rotella both have these. I am not a lubrication engineer but have done lots of reading and research in the last 40 years of building and raceing high HP engines. In these endeavors, I have used mostly Valvolline and Rotella oils and maybe just luckey but have never had an engine failure due to lubrication or the lack of! Most of this are observations on my part.
gtwitch in wyoming
gtwitch in wyoming