It really isn't important at all what brand of oil you use as long as it meets the viscosity requirements and API spec and/or manufacturer's spec for your engine.
I don't even bother to stick with one brand. I've used a lot of Mobil Delvac in my Kubota and Dodge Cummins because I can get it on sale in 5-gallon buckets. I've also used Rotella, Ursa, Champion, Valvoline and NAPA house brand (made by Valvoline). None of these are synthetic.
The one diesel I run synthetic in is a VW TDI with the PD engine and that is because VW specifies that synthetic oil be used. In that one, I run Pentosin 5w-40. It comes in 5-liter bottles. It's expensive, at $8 per liter or thereabouts. I'm sure it would make excellent oil for any diesel engine but if the specs don't call for it, you're just spending money needlessly.