We have a company that runs a fleet of buses running on diesel and Chevron (Caltex) had a test run on our buses using Delo400 as a standard.
The performance of the diesel engine displayed a marked improvement, together with efficient combustion and reduction in smoke.
We were also present at the launch where the results of the standards were displayed and since then, I would recommend the use of Delo400 being the premium diesel oil.
Give it a try. We did, and it worked.