Trucks: Junk science

What if you could pour a 12-ounce bottle of additive into your fuel tank and boost a truck’s fuel economy by 14 percent? Or maybe you could attach magnets to your fuel line. These magnet “catalysts” might energize, or “align” fuel molecules as they rush past, improving the engine’s combustion and fuel economy.

Sound too good to be true? That’s because it is. With fuel prices climbing almost daily, the temptation to find an easy way to stretch every tank of fuel can be overwhelming.

Unfortunately, there are many hucksters out there who are looking to cash in on high fuel prices by offering fuel additives or bolt-on components, claiming these products will significantly boost fuel mileage without any change in driving habits or additional maintenance demands.

To be fair, not all purveyors of fuel-enhancement additives or components are ill-intentioned. “I think half of them think their products actually deliver better fuel economy, but don’t really understand why they don’t,” notes Dr. Joel Hiltner, chief engineer of combustion systems for Hiltner Combustion Systems, an independent internal combustion research group. “On the other hand, I think the other half of that group know full well their products don’t deliver any benefits, but sell them anyway.”

Electrolysis and swirl inducers
There have been aftermarket products marketed with claims of improving horsepower or fuel economy since the birth of the automobile. And the products today target every conceivable vehicle component or feature: Some claim to optimize airflow over a vehicle to improve fuel mileage. Others claim to change the chemical makeup of fuel or engine oil, thereby enhancing specific beneficial characteristics in the combustion cycle.

Speculation that hydrogen may replace fossil fuels has led some companies to market hydrogen generators, which, they claim, use electrolysis to extract a tiny amount of hydrogen from water and inject it into the intake fuel stream for a claimed increase in fuel economy.

The overall premise sounds technically feasible. The problem, says Hiltner, is that the systems simply don’t work. “The electrolysis process requires more energy in the form of parasitic alternator loads to produce than the hydrogen it produces can return,” he notes. “In short, they consume more energy than they produce. We’ve studied several of these systems and found no boost to fuel economy or engine performance.”

Another popular after-market component are so-called “swirl inducers.” These are installed on the intake side of an engine. Manufacturers claim they swirl air coming into the engine, resulting in more efficient combustion and improved fuel economy and power.

“Any restriction you put on the intake airflow only degrades engine performance,” cautions Zack Ellison, director of customer technical support for Cummins. “And even if these devices did improve airflow somehow, that air still has to go through a high-speed turbo before it gets to the combustion chamber. And placing the device aft of the turbo doesn’t work. The air then has to travel through piping, a manifold and intake valves. So any ‘swirl’ imparted by the ‘inducer’ would decay almost immediately.”

Laboratory results to the rescue?
At first glance, all of these systems sound great. Except for one glaring omission: In the brutal battles between engine and truck manufacturers for customers, any truly beneficial fuel enhancement technology would immediately be snapped up by a manufacturer and offered as standard equipment. “If these systems worked, we would supply them to our customers as a matter of course,” notes Heather DeBaun, senior product engineer for International Truck and Engine. “And in some cases, fuel additives may harm an engine, most notably by negatively affecting after-treatment systems on post-2007 diesel engines.”

Many fuel-enhancement products often claim laboratory testing to back up their claims. Hiltner says you should still be skeptical. “A measurable increase in combustion efficiency in controlled laboratory conditions does not equate to real-world truck operation,” he says. “So it’s important to remember that lab results don’t automatically translate into an on-road fuel economy or horsepower benefit.”

Get to the truth
The Truck Maintenance Council has developed guidelines to help you determine if a product will deliver on claimed promises. When evaluating, ask yourself the following questions:

  • How long has the product been on the market?
  • Where can it be purchased?
  • What is its overall cost (initial, installation and cost per mile)?
  • What, and over what period of time is the return on investment?
  • Have any current users been successful with the product? Can you give me the contact information on three users?
  • Does the product affect emissions?
  • What is the product’s useful service life?
  • What maintenance is required?
  • What warranty is offered?
  • Will the product affect the life or warranty of the vehicle or its components?
  • Are there any handling considerations regarding installation, operation or disposal of the product?

For further reading, Cummins’ Zack Ellison suggests an overview on fuel-saving products commissioned by the Federal Trade Commission. It can be found at: