Gary is right on. Truth be told, virtually all the HDEO mineral base oil for the N. American market is made by one refiner..... Motiva (partly Shell owned). The majority of the add packs in the US are made by one producer.... Infineum. And the API specifications regarding something like CJ-4 is so tight, that there is very little difference between brands. The big name brands, you are paying for all their advertising, race car sponsorships, etc. The OEM brands are the same as the off the shelf brands. Most, if not all, of the OEM brands are packaged by one of the largest blenders in the US..... Warren Distribution.
I will concede that engines and oils are similar to .22 rifles and ammunition. While all .22 ammunition is made well, some rifles just plain tend to shoot best with a particular brand compared to another. Engines are much the same way. For some reason, an engine might favor a brand of oil. it is just one of life's little mysteries.
Shop for any brand of quality oil and get the best value you can. Doubt you will go wrong.
For the record, my engines, including the ISX in my semi, seem to prefer Mystik 15w40 I get at my local farm and home in 5 gal pails for roughly $11 a gallon over other brands I have used in the past. But to the OP point, I would have no problem using Delo 400 LE in my engines. As a side note: Delo 400 LE is meeting the 50,000 mile OEM recommended oil change intervals of the new Detroit DD15 engines. It must be a decent product.