I'm looking to drain the oil in my Powerstroke tomorrow to begin my first rinse phase and the oil I'm want to use is Service Pro 15w40 CI-4 Plus. I've looked at the MSDS for it and it lists its components as distilates, petroleum, hydrotreated heavy parafinic, solvent refined heavy parafinic, proprietary ingredients, zinc and zinc compounds. It doesn't say anything about PAO or esters so I think it should be all right to use.