There is also a reasonable following on the Power Service stuffs (which I use).

Basically two of their products are available in many places.

Diesel Fuel Supplement: This is one of those having everything type of additive, anti-gel, detergent, etc. It also contains some cetane boost (2 numbers if following their recommended dose or 4 numbers doubling dosage.).

DieselKleen: This is basically a cleaner but with more cetane boosts (3 numbers if following their recommended dose or 6 numbers doubling dosage.).

I like both of their products. A few week ago, I got a tank of diesel that just ran rough. I poured in 8 OZ of the DieselKkleen stuffs and it ran much smoother. The cetane rating is probably too low in some stations.