An extra edge

| April 01, 2006

Fuel additives may solve the problems of new ultra-low-sulfur fuel.

Diesel fuel bought at a quality outlet meets stringent requirements. Yet truckers worry about whether or not the fuel they are buying will be adequate for reliable and fuel-efficient performance.

Diesel fuel is complicated and has to meet complicated requirements because it does more than just provide the energy that keeps you rolling. Those requirements are laid out in ASTM D975, which all fuel refined and marketed for diesel trucks must meet, by law. But these minimum requirements don’t guarantee ideal fuel.

With 15 parts per million ultra-low-sulfur fuel coming onto the market by June, drivers and truck owners need to renew their attention to fuel additives. Every time sulfur standards have gotten tighter, the resulting changes in the fuel have posed new challenges, especially in the areas of lubricity and cold filter plugging. This time around will be no exception.

While marketers will observe standards regarding lubricity and cold plugging and will address these problems by blending in their own additives, the additives manufacturers have stepped up to the plate with products and recommendations that could give you insurance against trouble.

What can additives do to improve any fuel’s performance?

Lubricity agents
Diesel fuel must lubricate your injection system. The fuel the injectors force into the engine slips around the injector plungers – the parts in unit injectors that act like tiny pistons to pump the fuel – and between the needle valve and seat, providing lube just the way the oil from the pan lubes the pistons. Since the engine oil does not reach injector internal parts, running a fuel that won’t act like a high-viscosity engine oil can get you into injector trouble real fast. And engine manufacturers never warrant problems related to deficient fuel.

Especially with injection pressures that are higher than ever – at least 30,000 psi on the latest engines – “lubricity,” or the ability of the fuel to lubricate the injectors, is even more critical than it was a few years ago. Added lubricity agents help.

Even though fuel marketers will be adding a lubricity agent to the ultra-low-sulfur diesel to come, Mark Rossow, president and CEO of Advanced Fluid Solutions, thinks additives will be helpful. He says you should ask yourself, “Does the product have the necessary lubricity agent to offset the low sulfur?” Advanced Fluid Solutions’ product contains such an agent and has also been tested for compatibility with biodiesel, he says.

An additive with a lubricity agent not only lubes injectors and “helps prevent plunger wear,” says Forrest Lucas, president and CEO of Lucas Oil Products, Inc., because of the way a tiny bit of the diesel spray works its way over the top of the piston, it will help lube the rings and piston.

Lucas recommends an additive that will put some lubricity into the fuel, while also improving the fuel mileage. His company adds an exotic chemical that helps the fuel combust more rapidly. It has been tested and proven to give positive results at Auburn University, Lucas reports.

If an additive claims to improve lubricity, it should feel slick on your fingers, Lucas says. His company uses a “very expensive additive that makes the fuel very slick.”

Ken Stratton, vice president of retail sales at Power Service Products, recommends a year-round lubricity package, especially when ultra-low-sulfur diesel fuels hit the market.

Stratton says both their Diesel Fuel Supplement + Cetane Boost and Diesel Kleen + Cetane Boost contain Slickdiesel, a “powerful proprietary Power Service lubricator that provides maximum lubrication protection to pumps and injectors.”

Cetane improvers
Cetane rating refers to the fuel’s ability to ignite instantaneously. This helps you get faster starts at subfreezing temperatures. But it also affects the engine when warm. Diesels use mechanical control of burning, and the process doesn’t work well if the fuel doesn’t ignite right away. Have you ever heard your engine pop and crackle in an irregular way for a short time after a cold start? That is the sound of “ignition delay,” which can be a byproduct of low cetane even when the engine is warm. A “cetane improver” can help to give smooth and efficient running, especially when fuel is borderline.

Rossow generally supports the value of cetane improvers and mentioned that Advanced Fluid Solutions’ product includes one. But he cautions that with some of the latest injection systems, you should not overtreat because you can actually have too much cetane.

Some engines have something called “split injection,” and if your fuel is well above the required cetane rating, you could actually get pre-ignition. So compare the cetane rating of the fuel you are buying with the engine maker’s cetane recommendations and don’t add a cetane improver unless the fuel will still be within the recommended range.

Warns Stratton, “Many additive labels read ‘contains cetane,’ but unless the label specifically addresses how it affects the cetane number of the fuel, it probably contains only trace amounts of cetane.” Power Service has products that increase the cetane number four to six points, he says.

Lucas is a bit skeptical of the need for cetane. “The government requires a level of 43. That’s all you need,” he says. He believes you should avoid buying alcohol to mix with the fuel and get rid of moisture.

He recommends smelling a bottle of additive. If it smells exactly like kerosene or No. 1 fuel, it is likely to be little more than that.

Detergents
Injectors distribute the fuel in the combustion chamber in a very precise way. It’s a tough job, especially since the nozzle holes are unbelievably small and can easily clog partially due to deposits. The tip is exposed to high heat because it sticks right down into the combustion chamber. This heat can cause the fuel to form varnish and carbon deposits. A detergent will dissolve deposits, keeping the holes open and the fuel sprays forming an even mixing pattern. This speeds up combustion and reduces engine deposits and oil deterioration.

Additive packages may also include corrosion inhibitors and dispersants or emulsifiers. Corrosion inhibitors keep fuel from rusting metal injector parts, while dispersants and emulsifiers keep small amounts of water dissolved in the fuel. Water that separates can blow the tip off an injector.

Many additives claim to improve fuel economy. Stratton says Power Service Diesel Kleen + Cetane Boost provides an 80 percent fuel injector cleanup in the first 50 hours of engine operation, as measured in the Cummins L10 Injector Depositing Test. He believes you should look for cetane and detergent packages on a year-round basis.

Rossow reports that Advanced Fluid Solutions offers an additive that the Bible of the industry – the TMC/SAE Type II fuel economy test – proves actually increases fuel economy as much as 4.8 percent. Part of the product’s secret is a compound that “burns hotter and cleaner” than the base fuel to accelerate combustion. However, it also includes a potent injector cleaner. This will also increase mileage by removing carbon deposits in injectors to “give a complete spray pattern.”

While it is hard for an additive to improve combustion by modifying the fuel, if your injectors are starting to get dirty and a quality detergent additive cleans them up, you’re likely to see the fuel economy improvement mentioned on the package. Also, a couple of companies have developed very high-tech additives that actually help fuel burn better. You may want to try these out. But watch out for empty claims!

Anti-gels
Diesel fuel contains paraffin, a relative of candle wax. While the paraffin stays dissolved in the liquid fuel at normal temperatures, it will form solid particles at even moderate winter temperatures. These particles will form and glom together in the cold. The largest challenge is getting them through the filters, and this challenge is getting tougher. Filters today are much finer than they were even five years ago.

Once the primary filter, which is on the suction side, gets blocked, the fuel pump cannot draw fuel through, and you get stopped dead in your tracks. There are many anti-gel additives that keep the wax particles small enough to get through the filters. Proper use of them will help keep you going.

Lucas recommends being more careful to use an anti-gel with the new low-sulfur fuel because, “To get the sulfur as low as required, they have had to remove a molecule that kept the wax particles separated. You had better be heating the fuel, even with anti-gel.”

Fuel’s cold weather operability is measured in terms of its cold filter plugging point, the temperature at which it will no longer flow through a prescribed filter in a specified period of time, says Stratton. It is important to examine additive labels for CFPP reduction and “not simply pour point reduction,” Stratton says. “Pour point is not a true reflection of the fuel’s cold weather operability; cold filter plugging point is.”

Stratton reports that Power Service Diesel Fuel Supplement + Cetane Boost reduces CFPP as much as 36 degrees F. He recommends using this additive, which comes with a no-gel guarantee, during the months of November through March.

“However, common sense may dictate alterations to that rule of thumb, for example, during a cold April or if you live and drive in warm weather climates exclusively,” he says.

In extreme cold, using blended fuel that includes some diesel No. 1 may be advisable. However, No. 2 contains more energy and will give you more miles per gallon. So, if you can handle the problem with additives together with fuel heaters, it will save you money.

Diesel fuel is formulated by law to resist filter plugging at the prevailing temperature in the area where it is sold. But if confronted by a cold wave, or when using fuel bought in a warm climate to run into a colder area, the fuel’s ability to flow will be compromised. This is when it’s smart to use an anti-gel. Remember to use it before the fuel starts to gel.

“A driver heading north in the winter should always add a good anti-gel to their fuel before they hit the colder climates,” says Glenn Williams, vice president of Bell Additives. “Once the fuel begins to freeze up, adding the anti-gel is a moot point.”

Stratton warns that to be effective, an anti-gel must be added before the “cloud point,” the temperature at which the first wax crystals appear.

The additive won’t mix properly with solids formed by the cold and won’t be able to dissolve them. The only fix at that point is new filters. Preventive treatment is key.

Other additives
The high heat of today’s engines may cook the fuel, creating undesirable chemical changes that interfere with its performance. Stabilizers help chemically stabilize the fuel.

Algae and fungus sometimes grow where there is a thin layer of water in the bottom of your fuel tank. They can leave material that can clog your filters. Draining and cleaning fuel tanks may help, but some water and bacterial growth may be inevitable. A biocide can help protect you from an unexpected shutdown.

Many additives contain more than one type of fuel improver. “I personally recommend choosing a multifunction additive from a company that has been around long enough to really know what works and what doesn’t,” Williams says. “Pick a company with a good reputation and try out their additives for a few months.” Also, ask other drivers you trust what has worked for them.

With so many additive options, we advise you to read labels carefully and choose wisely, with an eye on your engine’s specific needs.

“Rather than individual ingredients that may or may not be included in an additive, drivers should look for the functions specified on the additive label and match these to their particular need,” Williams says. “For example, there are a number of ingredients that may help remove water from the fuel, therefore drivers dealing with water in their fuel need to reach for an additive that functions as a water emulsifier.”

Take care when choosing an additive not to sacrifice one benefit – say, long engine life – for another – say, fuel mileage. Williams warns against using additives that include “ferrous-type chemicals and compounds. These ingredients have been shown to have some benefit on increasing fuel mileage, however they do not completely combust with the fuel.” The remnants can damage the engine over time.

“The best defense is a good offense,” Williams says. “Drivers need to be assertive about getting on a regular maintenance routine of using good additives before they start to see problems.”


Blending Additives
Additives are relatively costly, highly concentrated products that modify a fuel’s behavior. They work most inexpensively at small concentrations. That’s why Lucas Oil Products, Inc.’s Forrest Lucas says there is a point with their additive past which doubling their treatment rate will not help a bit. Yet treating at 1/2 or 2/3 the recommended rate, “you won’t get the benefit.”

“Know what your fuel tanks hold and do the math,” Lucas says.

Make your calculator your friend, and mix at the recommended rate per gallon of fuel. Packages often are sized so one will treat 100 gallons, meaning you can just pour one full package into a typical full fuel tank.

Power Service Products’ Ken Stratton believes that on older fuel systems where the fuel does not circulate continuously back from the engine, “There may be some slight benefit to filling tanks after the additive has been added.” This will help it mix uniformly.

Diesel fuel has to do so much that you’ll be smart to doctor it with the right stuff. Read the package carefully, look for test results when an additive claims to improve fuel economy except by cleaning injectors, and make sure to keep your lubricity up and your cold filter plug point down.

Comments are closed.