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Diesel Soap Tech Bulletin

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Diesel Soap Tech Bulletin

Peter M Guerra


A new troubling phenomenon is occurring at times with Ultra Low Sulfur Diesel Fuel.The problem is called diesel soaps formation.Although not a wide spread problem yet,diesel soaps form when they react with surface active agents such as corrosion inhibitors.

Basically, The corrosion inhibitors that are added by the oil refiners at the rack contain salts that when exposed to water become acidic (actually the salt which is an acid combined with a base chemical separate into ions) These acids : (Dodecenyl succinic and Hexadecenyl succinic acid) react with fuel contaminants to form (soap like impurities) This was never a problem until the introduction of ULSD since these products were held in solution by the higher sulfur diesel fuels. With ULSD they can separate out and react with cations (eg sodium, calcium and other metal salts) commonly found in fuel tank water bottoms. Additionally rust and dirt may provide exchange sites that exacerbate the soap formation process.

The diesel soaps tend to plug filters, cause injector problems, fuel cloudiness and tank corrosion. Unlike asphaltenes which are dark, diesel soaps plug filters with a light colored gel material similar to what occurs when low quality biodiesel fuels are used repeatedly.

FPPF Solution

FPPF ‘s Diesel Fuel Injector Cleaner contains active ingredients that help dissolve these diesel soaps and eliminate the potential for filter plugging, injector problems and tank corrosion. Further our Fuel Power and the entire family of FPPF products containing Fuel Power also help to reduce the potential formation of diesel soaps. If and when the problem does occur we recommend multiple applications of FPPF Diesel Fuel injector cleaner as the best solution for diesel soaps problem. Use FPPF Fuel Injector Cleaner until the problem is eliminated.


New fuels, new engine technology, and new super fine filters mean diesel fuel additives are more important now than ever before.

Every fuel related problem is unique. From asphaltenes, fuel gelling, bacteria, fuel aging, low cetane, poor lubricity and now diesel soaps, FPPF products can solve your fuel problem. If you or your customers need further assistance, specific to your own situation, please feel free to call us a 1-800-735-3773 or call your regional FPPF Sales Representative. We will do our best to advise you on an action plan to best manage fueling your vehicles year-round.