Machinemover,
I know DC suggests that additives are not necessary if using quality diesel fuel. However, I have cured a low rpm. injector knock, with additives, that neither DC nor the dealer would fix after multiple visits to the dealer.
A lot of the fuel we are getting here in AZ is from CA & is ULSD. Up until recently, it has been very dry & low in lubricity, from what I've heard. Additives containing added lubricity were a good idea.
We have a military installation (Luke AFB) in the Phoenix area. Bosch has noticed a trend where communities near a military installation that used jet fuel were having an abnormal number of fuel system failures.
It seems that the military will refuse delivery of jet fuel that has the slightest contamination from diesel fuel. That jet fuel is sent to local tank farms, has additives introduced into the fuel to, hopefully, bring it up to diesel fuel standards, and then sold to us for use in our vehicles.
Sometimes, the additives aren't distributed evenly or in sufficient quantity. We buy it & possibly damage our fuel delivery systems.
For these reasons, in my opinion, using an additive is probably not a bad idea.
Joe F. (Buffalo)