Diesel fuel additive considerations
Meeting the demands of modern diesel engines
The commercial trucking industry is demanding more from diesel fuel. High-quality diesel is no longer a commodity — it has proven potential for optimizing modern diesel engine performance.*
Managers are looking to utilize the best fuel formulations, which has shone a light on additives and all-in-one fuels. However, finding the best formulation can be tricky.
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Fleets looking to enhance their diesel fuel formulation should seek input from their fuel providers on the current additive content of their supply, along with best practices for adopting new additives.
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Baseline additives
Standard additives blended during the refining process and at the pump enhance key properties consistent with a quality diesel fuel.* The most common additives include cetane improvers, lubricity improvers, corrosion inhibitors, conductivity improvers and cold flow additives.
- Cetane improvers may benefit cold start and reduce noise and smoke upon starting. These are added when the crude selection or processing does not result in an on-spec cetane number on its own.
- Lubricity improvers protect the fuel pump and injectors from wear and are required when the natural lubricity-enhancing compounds in diesel fuel are reduced (e.g., ultra-low sulfur diesel fuel). If a minimum of 2% fatty acid methyl esters (FAME) is present, they’re not necessary.
- Corrosion inhibitors help prevent corrosion of steel and copper or its alloys (e.g., brass, bronze) in fuel systems.
- Conductivity improvers help protect against static discharge during loading and are sometimes added again during the terminal stage, since their effectiveness can decrease with time and cold temperatures.
- Cold flow additives ensure diesel fuels can flow at the temperatures to which they’ll be exposed. Blending of cold flow additives depends on geography and season.
High-quality diesel fuels from reputable providers may contain one or more additives described above.
Providers’ quality assurance procedures should also be a consideration for fleets. At ExxonMobil, we help ensure our fuel meets specifications by testing it at our refineries, at the terminals and during transportation. If specifications aren’t met, additives are precisely injected into the fuel for vehicle performance and product quality purposes.
Additionally, fuel dispensers at Exxon™ and Mobil™ service stations have built-in filters to help preserve fuel quality as the fuel enters the vehicle’s fuel tank to help assure vehicle performance on the road.
Aftermarket additives
Unlike baseline additives that are blended at refineries and terminals, aftermarket additives are added by hand — often as an attempt to meet specific customer needs. High-quality diesel fuel should already meet required specifications without the need for aftermarket additives.
Aftermarket additives can cause more harm than good if not used properly. For example, aftermarket cold flow additives can interact poorly with baseline cold flow additives — resulting in filter clogs or improper flow. These additives may also become less soluble in cold conditions, preventing proper dissolution and mixing in some circumstances.
Enhancing diesel fuel is a science best left to the experts. Pre-blended fuel is much more likely to meet the standards for consistency, homogeneity and effectiveness.
Note: Detergent-based pre-blended additives can provide benefits for diesel fuel products by preventing or removing injector deposits. Detergent-based additives have also proven valuable for improving fuel economy, lowering tailpipe emissions and reducing downtime.
