Testimonials on the benefit of Cetane improvers are pretty much worthless because there are so many variables relating to the fuel to whitch the booster is added.
Diesel is primarily a blend of medium-weight hydrocarbons designated C8 - C21 (in contrast to gasoline which is a blend of lighter hydrocarbons C5 - C12). Diesel distilled from a crude oil base rich in C8-C21 will yield a high quality base diesel fuel with a high Cetane number; no additive required . Most modern refineries, however, are equipped with "cracking" units that break-up heavier hydrocarbon molecules (those heavier than C 20) . This makes diesel cheaper by adding heavy oil and asphalt to the available feed-stock for diesel; but it also results in a product with a lower Cetane number . When diesel is made from these inferior feed-stocks, the Cetane number can be improved by adding 2-EHN (2-Ethyl Hexyl Nitate) and other chemicals . The addition of 2-EHN, however, can only go so far . So if a batch of diesel started life with a poor feed-stock and has been improved with 2-EHN to the max, adding more 2-EHN from a bottle of after-market Cetane Boost with do nothing .
There are then three basic situations (with an infinite number of variables in between):
(1) Diesel distilled from high quality feed stock has an adequate Cetane number and adding a Cetane boosting chemical is worthless .
(this situation is likely rare in the US owing to the prevalence of sophisticated high-yield refineries that are tuned to "get all the squeak out of the hog").
(2) Diesel made from a low quality feed-stock that has been treated to the max with 2-EHN and other enhancers cannot be improved by adding more such chemicals from a bottle of after-market Cetane Boost.
(3) Diesel made from a mid-quality feed-stock that has had only a little 2-EHN added at the refinery, can be improved by adding more of the same from a bottle of Cetane Boost.
So whether a bottle of Cetane Boost really increases the Cetane number of a given tank of diesel depends on the chemical composition of the last fill-up (this is why the bottle says "improves Cetane up to 4 numbers"). And, don't think that one fill-up will be anything like the last, even if you always use the same station . Many (if not most) refineries run different batches of crude each week, leading to constantly differing mixtures of diesel feed-stocks. AND wholesale distributors that supply filling stations are constantly receiving different batches from various refineries. Only a tiny minority of stations are in a supply chain that delivers the same diesel mixture throughout the year.
Add Cetane Boost if you can afford it (I always do). On some infrequent occasions it might actually be doing some good.
hey CatDriver, are you on the Sprinter forum? I read the exact same post over there!