I have been trying to find out the concentrations of Zinc and Phosphorus (specifically interested in ZDDP levels) for Shell Rotella T diesel single weight oils (primarily 30W) which currently is API CF-4. There is some info out there saying that the 15W40 mutiweight oil has 1200 ppm Zinc and 1100 ppm phosphorus (CJ-4). Anybody have an idea of if the single weight concentrations of zinc and phosphorus are ? I am led to believe that they are the same as the mulitiweight 15W40 OR that they have reduced levels in the order of 1000ppm Zn and 900 phosphorous (in between API SM rated passenger oil and API CJ-4 diesel oil). I am trying to calculate an estimated total Zn and Phosphorus level (ZDDP) when using the Shell Rotella T 30W in combination with ZDDP additives such as ZDDPlus. I want to get the right concentrations for cam breakin and cam maintenance. Thanks.