Skip to main content

A sampling of fuel additives

The claims are plentiful, so we spoke with five companies to see how their products work

The claims are plentiful, so we spoke with five companies to see how their products work

Manufacturers formulate additives in different ways to treat a variety of fuel problems. Here’s a look at five manufacturers, with information about product formulations and some of the claims they make for their additives. I should emphasize that I’m not recommending any one product over another. And the omission of any product or company isn’t intended to imply that the product isn’t as good as any other. Also, neither I nor Soundings conducts independent testing.


ValvTect Marine Fuels ( ) doesn’t sell just an additive. It sells ValvTect Marine Gasoline and Premium Diesel — with additives already in it — to ValvTect-certified marinas and fuel docks. Tanks, filters and other features of these fuel facilities must be inspected and approved by ValvTect representatives. This includes ascertaining that the tanks are clean and contain no water or other contaminants, such as bacteria or algae.

“We have formulated ValvTect Marine Premium Diesel with BioGuard biocide, lubricity improver, water dispersant, corrosion inhibitor and fuel stabilizer to prevent problems caused by the reduced sulfur content,” says Jerry Nessenson, ValvTect president. “ValvTect Marine Premium Diesel requires no additional fuel additives, thus eliminating the risk of using the wrong fuel additives, saving time and a lot of money.”

He says the extra cost to the retailer for ValvTect Marine Fuels is usually about 3 cents a gallon, though retailers may charge more to the customer.

ValvTect’s water dispersant is an emulsifier that keeps water in suspension, Nessenson says. The industry standard for water content in diesel is 500 ppm. Nessenson says diesel usually leaves the refinery with 50 to 80 ppm of water, but moisture can build up in the fuel while it is in the tank at the marina or on the boat. A good water separator filter on the boat can remove — within limits — harmful amounts of water suspended in the fuel.

He warns against using some over-the-counter additives that can cause water to sink to the bottom of the tank, resulting in a high water-to-fuel ratio that breeds bacteria and forms sludge. Other additives have too much glycol, which absorbs water but can cause engine problems or even engine failure. Alcohol- or methanol-based additives should never be used, he says.

ValvTect’s BioGuard isn’t fuel-soluble like some biocides, Nessenson says, which means that instead of remaining in suspension, it settles to the bottom of the fuel tank, where the bacteria grows and where the biocide is most needed. He says tests show BioGuard is 90 percent faster-acting and more effective than fuel-soluble biocides.

Nessenson says biodiesel treated with ValvTect diesel additive with BioGuard prevents problems sometimes associated with untreated biodiesel. If you don’t have a ValvTect fuel dock in your area, you can buy ValvTect’s additives at marine supply stores. See

ValvTect Marine Gasoline contains additives that can prevent problems associated with ethanol blends, such as octane loss, poor stability and phase separation, he says. However, if a large amount of water gets into the fuel and causes phase separation, he says, no additive can safely correct the problem. It is best then to hire a professional to pump and clean out the tank.

Nessenson says ValvTect’s performance claims are substantiated by petroleum industry tests under SAE and ASTM test standards and protocols. He says the tests show ValvTect gasoline and diesel improve fuel economy 8 percent when used continuously. Also, he says the tests show the fuels remain stabilized up to a year without additional additives.

Star Tron

Star brite ( ), supplier of an array of hardware, cleaners, polishes, treatments, adhesives and other products, also markets various gas and diesel fuel additives, including a biocide, a water absorber and stabilizer, and an enzyme-based product called Star Tron.

Different from most additives, Star Tron is a blend of enzymes, complex proteins that act as catalysts in starting and/or speeding up biochemical reactions without itself being changed or used up, according to Star brite vice presidents Jeff Tieger and Bill Lindsey. They say Star Tron’s enzymes do a number of helpful things. For starters, they keep water molecules from bonding with each other, a problem with fuels containing ethanol. Star Tron also reduces surface tension of water molecules, they say, and helps microscopic water drops remain in suspension so they can be removed by a good water separator filter or burn through during ignition in small amounts.

The higher-octane rating of ethanol gasoline comes in part from the ethanol, but unless it is burned right away the ethanol can combine with moisture, drop out of suspension and accumulate with water just above the bottom of the tank, causing the fuel to lose some of its octane rating. Star Tron’s enzymes help eliminate water accumulation, keeping the ethanol molecules in suspension, they say. Also, Star brite executives contend the enzymes stabilize fuel and enable more oxygen to attach to it at the point of ignition, producing a more complete fuel burn, more power per gallon and fewer emissions.

Star Tron’s enzymes do other jobs, as well, according to Tieger and Lindsey. For example, over time they help break down and disperse the sludge formed when water and ethanol drop out in gasoline. In diesel, while dispersing water, the enzymes also disperse “diesel algae,” the tar-like stuff that grows in the water on the bottom of the tank. They say Star Tron helps the filtration system work more efficiently and in time cleans a diesel tank completely. Smaller particles pass readily through the fuel filters and burn harmlessly in the engine, while larger particles are removed by the filtration system. Star brite says enzymes also remove gum and carbon deposits in a combustion chamber without solvents or detergents.

Users at first will notice more smoke in the exhaust, a result of enzymes dislodging and dispersing deposits and contaminants that burn through during ignition, the company says. This stops as soon as the tank is clean and deposits are removed, it adds. Star brite also says that when using its product in fuel that’s carrying a lot of sludge, an owner likely will have to change filters often while the gunk works its way out and larger particles are captured.

Star brite officials say Star Tron has been marketed to industrial and commercial users for about 10 years by Solpower ( ), as Soltron and XBee. Solpower says it “has conducted many ‘industry-standard’ empirical studies on the performance and environmental safety of Soltron Enzyme Fuel Treatment (XBee and Star Tron) in laboratories around the world.” However, it also says some Soltron claims do not have a standardized fuel-lab testing protocol that “accurately duplicates real-world application of the enzyme technology.” The claims of removing sludge and dispersing bacteria are based on fuel modification analysis or field studies of customer experience and opinion, it says.


Today’s gasoline is treated at the refinery with a small amount of “deposit modifier” detergent, as required by the federal Clean Air Act, but the effectiveness of these detergents is limited, says Ralph Lewis, a vice president at Power Research Inc. of Houston ( ), manufacturer of additives PRI-D for diesel and PRI-G for gasoline. Over time, unburned hydrocarbon emissions form solid carbon deposits on pistons, exhaust valves and injector tips, and the problem grows as fuel ages, he says. Deposit modifier gasoline additives do have some mild detergent and stabilizing properties, he says, but it’s not enough, and there is no federal mandate for diesel fuel additives. PRI makes a stronger, more effective, industrial version of detergents added at the refinery, says Lewis.

With any petroleum fuel, there is a “cracking” process during combustion — a point at which hydrocarbon chains break apart and recombine into very dense, high-carbon-weight material that results in more emissions and deposits. PRI chemistry is designed to prevent these heavy-carbon materials from forming during cracking, thereby eliminating most unburned carbon, Lewis says. This results in greatly reduced smoke at lower operating loads and better-running engines, he says. Also, PRI additives keep fuel fresh in long-term storage.

PRI-D and PRI-G sold at retail use the same industrial-grade chemistry offered to the company’s industrial clients, which have strict criteria for product performance, Lewis says. He says there are standard tests that measure an additive’s capability to retard fuel degradation, and they substantiate his company’s claims. He says two of these that have proven PRI’s effectiveness as a diesel additive are the ASTM D2274 and Octel F21-61 tests, and another, ASTM D525, validates PRI’s claims for gasoline. One of those tests heats diesel fuel over a set time, then filters the fuel. The residue created by the heating is measured by weighing the filter that catches it. So far, no other chemistry has exceeded PRI’s capabilities in these tests, Lewis says.

Lewis says the Tennessee Valley Authority used PRI-D to treat 1.8 million gallons of badly degraded diesel at one of its power plants, and restored the fuel in two weeks. HFO-fired (heavy fuel oil) power plants also use PRI technology to reduce emissions, and commercial vessels operating on HFO use PRI’s HFO formulation, PRI-RS, to cut emissions and deposits, he says.

Much recent concern about the lubricating properties of ultralow-sulfur diesel is unfounded, Lewis claims. Refiners typically add lubricity additives to this fuel at distribution terminals. However, to ensure against the possibility of inadequate treatment, PRI puts a lubricity additive in its PRI–D, he says.

PRI-D isn’t a cetane booster like some diesel additives. Lewis says today’s diesel fuels already are high in cetane because refiners use cetane improvement additives, so there’s no reason to buy an additive to increase cetane.

Biobor JF

Biobor JF is an EPA-approved biocide manufactured by Hammonds Fuel Additives of Houston ( The diesel additive is one of a handful approved by major aircraft manufacturers for use in aviation and recommended by many marine diesel manufacturers, says Jerry Anderson, the company business development manager.

The product literature says Biobor attacks hydrocarbon-utilizing microorganisms known as HUM bugs and technically named Cladosporium resinae and Pseudomonas aeruguinosa. These organisms multiply rapidly, sometimes doubling in mass every 20 minutes and eventually forming dark-colored mats. Their byproducts include water, sludge, acids and other contaminants, according to the company.

Anderson says Biobor remains in suspension and doesn’t drop to the bottom of the fuel tank. Product literature says the product “must be kept from direct contact with excessive amounts of water to prevent hydrolysis of active ingredients into fuel-insoluble materials.” However, the company reports this has never been an issue with its customers, nor is it something that would occur in normal use. The label on the bottle says Biofor does its job in 24 to 36 hours.

Anderson says the product kills microorganisms not only in the fuel but also in water at the bottom, as the organisms try to “eat” the fuel above them. He says it isn’t designed to emulsify already-formed mats of HUM bug, but as Biobor begins to kill the microorganisms the slimy material at the fuel/water interface begins to break up and fall to the bottom.


Sta-Bil has been around for more than 40 years, but manufacturer Gold Eagle Company ( recently formulated a product especially for marine use that is a distinct blue-green teal color instead of the old red color, says Tom Wicks, Eagle product engineer manager. Marine Sta-Bil Ethanol Fuel Enhancer contains chemicals to prevent gum and “varnish” deposits in the tank, a corrosion inhibitor to help combat water that may be picked up by ethanol, a metal deactivator to help prevent corrosion, an antioxidant to stabilize fuel, and a PIB amine detergent dispersant to clean carburetors and injectors. It contains no alcohol, he says. The product has been tested following ASTM D525 and National Association of Corrosion Engineers standards for corrosion tests, as well as others. It is designed for use with gasoline, but marine Sta-Bil also will treat diesel fuel, the company says.