You might find this site helpful for servicing your engine:
I would recommend visiting or calling a shop familiar with Universal diesels and getting their recs on oil choice, especially if you live in a seasonal climate. Alternatively, you could email the folks at the web site above...and maybe even order a shop manual, which will pay for itself in short order.
One grade of oil is not suitable for all engines under all conditions. Best you learn what''s suitable for your location and engine.