I've never understood the "need" to add aditives for lubricity,
Save some money and don't worry about lubricity.
Okay let me help you, old diesels were made to run on... diesel... not this ULSD stuff... it had a certain lubricity that everything expected... why do you worry about using 15w40 diesel oil... I mean oil is slippery right? Should not matter?
So now with ULSD, we have a lubricty spec... not only can you find tests of pump fuel that is *above* this spec (bad) you can look around and see EVEN if pump fuel meets spec... it is still *HIGHER* than what current common rail diesels recommend...
So, current ULSD does not even met the spec for *New* diesel systems... you find no reason to add some to older diesels? Also most are also a cetane boost... let's look at the rating the US has... Oh right, compared to the rest of the world it is *junk*.
Adding some cheap (the opti lube I spoke is of a min dosage (summer) is 2500+ gallons / $ 55ish) additive that should add extra lubricity, clean, as well as separate water.... and "boost power / mpg" cause... cetane... (even if it's so little... it might offset the additive cost...)
Why not.
I doubt you have 2 million miles on 1 truck...
If you want to google around enough you will see many places blame common rail injector issues on... fuel quality. Again, US spec does not even meet bosh spec for common rails... so... if you want to be in manufacture spec (for current diesels idk spec on cuvcs) you need to add stuff...