i use rotella in mine, its just what i've always used in the diesel
powered tractors so when i bought to ctd it was on hand *shrug*

i know people who have used DELO haven't heard any complaints. and there
will be people here on the synthetic side of things. any oil recommended
for compression fire engines should be fine.

First, I'd recommend an overhaul on your keyboard....  your caps lock key
seems to be mis-firing.

As far as oil, I don't spend the extra money on synthetic, because it gets
changed every 5,000 miles (I change it more frequently than suggested, due
to a bunch of modifications that tend to dirty the oil up quicker).  The
most popular brands used are Shell Rotella, Chevron Delo 400, Mobil Delvac
1300, and Valvoline Premium Blue - all in 15W40.  One's just as good as
another in terms of performance.  I used to run Rotella, but switched to
Delvac due to the somewhat unpleasant odor of Rotella shortly after an oil
change.

I like the oil that lubricates that is the kind I use and 115k with just oil
and still going.

Coasty