Rotella is some nasty crap I run delo it holds up better imo but then again I don't change my oil as often I just change the filter even the oil guys from cheveron say oil doesn't really go bad so to speak it just gets dirty but that's what I've been told

 

Not smart - especially with a diesel, because...
This is true, to a certain extent. Dispersant, anti-oxidant and other additives do get used up/depleted over time. The big problem with diesel oil getting "dirty" is soot - soot that is submicronic and does not get trapped in the oil filter. The oil's job in a diesel engine is to suspend that soot in solution and carry it out of the engine DURING REGULAR OIL CHANGES.

Left to it's own for long enough, the oil's ability to control soot becomes depleted/overcome. Then the soot begins to conglomerate into larger particles that drop out of solution and stay wherever they get stuck inside the engine, clog the filter, etc. It goes downhill pretty fast after that.

The only way to properly do the filter-only thing is with supplemental bypass filtration.