How Fuel Additives Can Help Diesel Engines
Diesel engine vehicles typically operate more efficiently than their gasoline engine counterparts, but the nature of diesel fuel can cause drivability issues. Diesel fuel additives can help, but only as a short-term solution.
Water and Dirt in Diesel Fuel
Diesel problems can start even before the fuel is pumped into your tank. Diesel fuel delivered to gas stations is not necessarily clean and free of contaminants. In a 2016 study, Donaldson Filtration Solutions found that a single delivery of 7,500 gallons of diesel fuel contained one to two gallons of water and a cup of dirt. Once delivered, even more water and contaminants can be added to the fuel due to poorly maintained storage tanks at fuel retailers.
Fortunately, diesel fuel systems have water separators to extract moisture and fuel filters to capture other contaminants, and both protect expensive fuel injection components and help prevent problems. Critical maintenance steps for diesel engines include periodically draining the water separator and replacing the fuel filter.
Be Aware of Diesel Engine Drivability Issues
Even if you maintain proper maintenance and use high-quality diesel fuel, your engine may still encounter drivability issues.
- Microbial Growth – If too much water accumulates in the fuel tank, it can “fall out” and settle at the bottom of the tank. When this happens, bacteria and fungi in the fuel can multiply, forming a black slime that can clog fuel lines and filters.
- Freezing – Water retained in the fuel tank or water separator can freeze in winter, blocking fuel flow and preventing the vehicle from starting.
- Fuel Gelling – Diesel fuel contains paraffins that freeze in cold weather, forming a wax-like substance that blocks fuel flow. This occurs at lower temperatures than freezing.
- Fuel Stability – Diesel fuel stored for long periods can become unstable and break down, forming gums that clog fuel filters and create deposits in the fuel injector and combustion chamber.
Diesel fuel additives help combat these issues. Automakers, however, caution against using additives as short-term solutions for specific problems, and not on an ongoing basis.
What to Know When Using Diesel Fuel Additives
- Measure twice and treat once. Additives are designed to work with specific amounts of fuel. For example, 16 ounces of additive can treat 30 gallons of diesel fuel. Over-treating a fuel system with too much additive can damage expensive fuel injectors and the injection pump.
- Get more for your money. Many additives bundle multiple treatments into one product. For example, a diesel fuel “conditioner” may include water absorption capability, an anti-gel agent, and a fuel stability enhancer in a single bottle.
- A wide range of high-quality diesel fuel additives are available on the aftermarket. Before purchasing a product, check your owner’s manual for specific precautions regarding the use of additives.
- Automakers test and recommend their own brand of diesel fuel additives or those from a designated supplier. Remember that using an unapproved additive may void the fuel system or engine warranty if a problem can be linked to the additive.