Have you witnessed the “white smoke” any other time you have started it? After sitting for a month, I would assume a significant amount of condensation would have built up in the exhaust, and was probably steaming off once it was warmed up enough. If you haven’t seen it since, I wouldn’t worry about it.

As far as the turbo, I thought most were oil cooled.

The Rotella T-6 is also available at Walmart in 1 gallon jugs for $22. Chevron has their Delo synthetic diesel oil for $19 or so. I run the Rotella in my diesel liberty.