FWIW, everybody has their own favorite.
I have used oils from Amsoil AME, Mobil TDT, Walmart Supertech, Mobil Super 1300C, Rotella, etc.
Everything is within the spec and the truck is still running.
So, just pick one of the Diesel rated oil and it should be fine.
They are all within the spec to run this old truck.
I agree with Twisted.
Let me clarify what I am saying.
The best oil based on performance (longevity, protection, specification, etc.) is probably suggested by Twisted, the TriboDyn.
He is correct, if people try it, they probably don't want to go back to other oil.
Now, in terms of economy, at least in my mind, it depends on the driving pattern and the condition of the truck.
Driving pattern considering factors like how many miles driven per year, what is the road condition, towing/non-towing, etc.
For my truck, this is the 2nd vehicle so I only drive it within 3000 to 5000 miles a year in the past 10 years.
This year will even be less than that due to the condition that happen right now.
I am not towing, the truck mostly driving in town.
So, the question is putting an oil that cost $20 per quarts worth the money.
Next, the truck condition.
I started the truck by putting Amsoil which is not as expensive as TriboDyn but it is expensive.
The only way to make it worth is by extending the oil change interval which I did.
Then I found out that the engine is burning oil or there are oil leaks from the oil cooler lines (which normal for this truck).
So, putting an expensive oil which is mostly used to oil the road is really not feasible????
Then, I just used the Cheap Wally's Supertech.
At least until, the oil leak is fixed.
After that, I just used the on-sale synthetic diesel oil or Delvac Super 1300S Dino.
The truck will always leak oil somewhere so my reasoning is using the cheaper oil is more sensible.
Not that I don't want to preserve my truck but the value is no more than $3000.
So, there you have it.
If your truck is in tip top conditions, the by any means use the TriboDyn.
You can probably goes 10K OCI or even longer OCI (20k to 30k) with External Bypass oil filter.
But if the truck leaks in any way shape or form, then even the 10K OCI is never going to happen.
You will have to refill every 1000 miles or so.
In which case, you probably don't need to drain and fill oil change since the oil is changed automatically. LOL!!!