This is a common question and a good one. I was doing some reading on this subject. Both Cat and Cummins say you don't need any additives. The big caveat is "if the fuel meets the required standards." Now how do we know if the fuel meets all the requirements? Now it is interesting that Cat says that additives will not improve performance but may "restore" performance. They now recommend 256-4968 Caterpillar fuel conditioner can improves mileage by 2-3%. They also recommend, 343-6210 Caterpillar Fuel system cleaner.
Cummins only approves products manufactured by Cummins or it’s subsidiaries.
https://www.cumminsf.../LT32599_08.pdf
So while saying you don't need additives they sell and recommend them.
I am going to continue to run the Fleetguard Asphaltene Conditioner or Diesel Kleen.
Hear is a link to a test of additive that "The Diesel Place" did on several additives.
http://www.jatonkam3...ditive_test.pdf.
I posted this on a different forum and copied it hear to save typing.
Bill