Ok, thanks for the posts, but can we not attack each other's opinions or source data, please? There's enough hostility going on these days, let's have some fun in here with expert engine people.
I'm no oil cult worshiper - I'm a trained scientist. Diesel Fuels do not appear to be regulated to the degree gasoline is. There is no "Top Tier" fuel definition for diesel fuel as there is for gasoline. I worked for Cummins - we tested the local available diesel fuels for our test cell work - some were under 40 cetane. Some were over EPA sulfur limits. The corporate parent had access to 45 cetane fuel and used it for their test work. We complained this was not representative of the national fuel supply but couldn't get them to back down to 40.
Some older engines benefit from higher cetane, at least, and some from additional cleaning agents. In addition, our regional fuel supply mandates soy-based biodiesel (big farm lobby). For those that don't consume fuel regularly, a biocide at least is needed. Here we are forced by state law to use B20 biodiesel in summer and B10 biodiesel in winter. You know the gel point of B10, right? The weather gets to -20F here in the winter.
I have a Yanmar tractor engine the "requires" 50 cetane minimum fuel. Why? Well, it's old-time IDI pump-line-nozzle fuel injection, naturally-aspirated. It's in a John Deere 1000 series compact tractor. There's thousands of these things in the US, and in boats, etc. The Japanese and Europe have easy access to 50 cetane diesel fuel. I do not.
Fuel quality is legit issue for many of us - please don't respond with whether you "believe" in additives or not. I asked for your experiences.