I work for the school system here in San Diego. Speaking to the top diesel tech here,he cannot remember a single fuel quality related problem to any vehicle here. We're talking Internationals,Hino's,Isuzu's,Cats etc. He has literally hundreds of diesel vehicles(mostly late model,aside from our Hino's & Isuzus) that he's responsible for. A fair amount of sensor problems,but nothing fuel related he can put his finger on. That being said,I'll keep using Standyne. P. S. We do have state mandated, recently installed and constantly re-checked underground tanks,and a tanker-a-day diesel habit assuring fresh supplies.