How Diesel Fuel Additives Work
By BRETT WINBERG with reference from Truck Info

With the weather causing major concerns around Canada and the United States this time of year, an article about the use of aftermarket fuel additives seems only appropriate. These additives can assist the small truck market, over the road market as well as mining and construction markets achieve the most efficiency out of their equipment.

Diesel fuel additives are simply chemicals that change the properties of untreated diesel fuel.

The biggest users of additives are refineries and distributors. Each batch of crude oil is different from the next, and each batch of refined diesel fuel is different from the next. Refineries and distributors use additives in bulk to make their diesel fuel more consistent before they sell it. This is called the “pipeline specification”.

DO ALL BOTTLED DIESEL FUEL ADDITIVES WORK?
Most bottled diesel fuel additives work. They contain, in bottled form, the same chemicals as the refinery uses in bulk to change the fuel.

Less reputable brands… which you should avoid fall into three categories:

• Some less reputable brands have no active ingredients.
• Some less reputable brands have alcohol as the active ingredient. Alcohol gives a short-lived boost to combustion but it wears off in a few moments, and alcohol attacks seals and gaskets.
• Some less reputable brands have light engine oil as the active ingredient. Light engine oil makes an engine run smoother, but it fouls injector tips with repeated use. It also lowers energy content, horsepower, and mileage. The operator may even get the opposite impression because he shifts gears less often. That’s because he has to run in the wrong gear in the first place.

Most additive brands are reputable; they do contain chemicals that effectively improve the fuel, and do so without harmful side effects.

An additive won’t work if the operator uses it for the wrong application. They must understand what the additive is supposed to do. Specific problems require specific treatments. There is no magic “does-it-all” chemical. If the additive isn’t clear about what it does, or the user isn’t clear about what he/she wants, then the additive may not give any added benefit.

It’s worth mentioning that NCWM defined five properties of diesel fuel and set standards for calling it “premium”. The five properties are energy content, cetane number, low-temperature operability, thermal stability, and fuel-injector cleanliness.

Does an operator get good energy content, cetane number, and low-temperature operability in certain months, thermal stability, and fuel-injector cleanliness if he buys a “premium” fuel? Not necessarily. A refiner or distributor can call it “premium” fuel if the fuel meets any two of the five standards. Low-temperature operability does not apply in most months and in many locales, so a “premium” fuel assures an operator of only one standard.

For instance, the NCWM standard for cetane in “premium” is 47. A study found one “premium” grade fuel with a cetane of only 35, which is actually below the federal minimum standard of 40 for regular grade diesel. An operator hoping for a certain cetane number from this “premium” fuel would be badly disappointed. This situation is not rare. The most recent Premium Diesel Fuel Survey from Hart’s Diesel Fuel News shows that 26 major refiners/distributors make 34 brands of premium diesel fuel. Only one of the 34 brands of premium fuel claims to meet all five NCWM properties. Thirty-three of 34 admit to falling short on one, two, three, or four properties. Another study of 64 “premium” fuels showed none meeting all five standards.

WHAT CAN ADDITIVES DO ABOUT “GOOD ENERGY CONTENT”?
“Good energy content” translates to more miles per gallon. How does an operator assure himself or herself of good energy content if it doesn’t come out of the pump? The refiner can’t fix this with additives and neither can the operator. If it’s winter, the cause might be dilution with kerosene for low temperature operability. They should find another fuel that doesn’t have kerosene, and treat it with their bottled anti-gel additive. If they have to use this fuel, we only hope he’s paying less money because they are getting less power.

WHAT CAN ADDITIVES DO ABOUT “LOW-TEMPERATURE OPERABILITY”?
“Low-temperature operability” means the fuel won’t gel up and clog the fuel lines or fuel filter. Most fuels from the pump are treated in bulk with additives or kerosene. Some meet a specification, some do not. If they don’t meet a spec, or if the weather becomes colder than the spec, or if the equipment is headed to a colder area … then gelling is a risk. The operator first wants a water removing additive, because ice forms faster than wax gels. Next there are preventative anti-gel additives to give more protection than the fuel from the pump. There are also remedial additives which un-gel fuel that has clogged the fuel lines or fuel filter. TIP: it’s better to prevent than to cure.

Remember with the new ULSD fuels having to be used in today’s market, the pitfalls are cold weather performance and alarming low levels of sulfur. With weather around the world mostly being winter, “except you lucky folks down under”, fuel gelling is a major concern for all diesel equipment. Be sure to use a tested Anti-Gel that will protect to (-25 Deg F) or better to assure your equipment will start and run properly.

WHAT CAN ADDITIVES DO ABOUT “THERMAL STABILITY”?
“Thermal stability” means the fuel’s ability to resist particle formation as it circulates from the tank to the engine and back again. Such particles clog filters and injectors. Operators using high-pressure injector systems with fuel as a re-circulating coolant can easily assure thermal stability with a bottled additive.

WHAT CAN ADDITIVES DO ABOUT “FUEL INJECTOR CLEANLINESS”?
“Fuel-injector cleanliness” means the fuel has a detergent that keeps clean injectors clean. Injector tips are precision instruments. Even a little dirt or varnish will damage proper spray pattern and combustion, waste fuel, rob power, and reduce mileage. Dirt is caused by thermally unstable fuel. Dirt is caused by worn needles and over-rich fuel feed; needle wear is caused by water abrasion. Varnish is caused by suspended water in the fuel. You can stop the causes of dirty and varnished injectors with regular use of water removing and thermal stabilizing additives. You can clean larger accumulations of dirt with an additive that contains a high concentration of detergent. Cummins L-10 is the accepted specification for detergency. You can keep clean injectors clean with a fuel that contains detergent.

WHAT CAN ADDITIVES DO ABOUT “LUBRICITY”?
The joint definition of “premium” grade by TMC and EMA uses the same properties as NCWM. TMC and EMA standards are a little tougher. For instance, their minimum standard for cetane is 50 compared to 47 for NCWM. TMC and EMA definition adds lubricity as another property. (In fact, lubricity was discussed by NCWM as a sixth property. “Lubricity” means the lubricating value of fuel. Low sulfur fuel has less lubricity. Low sulfur fuel also absorbs water more readily, and water is an abrasive. Untreated fuel often causes excessive wear on fuel pumps and injector tips. Many additives have a lubricity improver, by itself or in combination with other chemicals. Using the ASTM D6079 testing method will show if your fuel and or fuel additive can increase the lubricity of the product. It is very important to know the value of lubricity of the fuel additive you are using or going to use.

ARE BOTTLED ADDITIVES A GOOD DEAL?
Generally yes. Premium diesel is 5¢ to 15¢ per gallon higher than standard. You are assured of good quality in one to five important properties of diesel fuel. Additives cost 2¢ to 4¢ per gallon to assure good quality in one important property of diesel fuel: to remove water, to clean injectors, to lower pour point, to boost cetane three numbers, or to add lubricity. Combination additives assure good quality in several important properties of diesel fuel, and cost 5¢ to 10¢ per gallon. In most cases - but not all -- you’ll get more benefit for less money by using bottled additives.

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