I have a 2005 E450 6.0 diesel that is blowing white smoke out the exhaust.
Water and oil are not mixing from what I can tell
Could it be the oil seal leaking at the turbo causing this?

This link may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1977241