uncategorized · 10/10/2019

Get the Dirt on Diesel Contaminants

Get the Dirt on Diesel Contaminants


Written by Matt Leuck

How much is fossil diesel really costing your fleet? Industry surveys show that diesel contaminants are the number one cause of poor engine performance. And fuel issues are the leading cause of equipment failure. As delivery windows and budgets continue to shrink, make sure your fuel isn’t slowing down your fleet.

Engine technology is evolving. Fossil diesel hasn’t caught up.

Advancements in diesel engine technology have improved performance, increased miles per gallon, and reduced emissions, but even the most innovative engines can be held back by conventional fossil diesel. 

The latest engine designs have evolved to meet more stringent emissions regulations, such as those in states like California, where Governor Jerry Brown committed the state to “remove as much carbon dioxide from the atmosphere as it emits” by 2045. Yet these modern engines require a much higher level of fuel cleanliness and care. It’s now more important than ever to prevent and manage fuel contamination.

In the past, maximum diesel fuel system pressures rarely exceeded 3,000 psi, but today's advanced systems can be as high as 30,000 psi. These high pressures, and the subsequent chance for increased wear of the injector housing, can cause fuel to enter the combustion chamber before or after combustion. When this happens with fossil fuel, it can create a buildup of soot or dilution of the engine oil, leading to reduced viscosity and increased engine wear.

Fossil diesel and its contaminants can cause engine issues.

Water and dirt—accumulated during transportation and storage—are the most significant contaminants in diesel fuel. Water and sediment lead to rust, corrosion, and filter blockage as well as wear on pumps and injectors.

Hard particulate matter, commonly referred to as “dirt,” causes problems with moving parts in the fuel system. Dirt can lead to problems with starting, poor engine performance, idling issues, and potentially complete engine failure.

Water can create a host of issues. The acceptable water volume in diesel should be well below 0.05 percent; any more, and the life of the injector could be cut by half. But the injector isn’t the only piece of equipment at risk.

Microbial growth in fuel storage tanks is the single biggest cause of fuel problems and destroyed fuel quality. It can plug filters, change the pH of stored fuel, and cause damaging tank corrosion. Whenever there is water present in a storage tank, microbial growth is sure to follow—quickly.

Microbes do not readily grow in renewable diesel. This alternative fuel contains no aromatics or impurities, decreasing the frequency of injector maintenance and diesel particulate filter (DPF) regenerations.

Advancements in alternative fuel technologies can keep your fleet running smoothly.

With a cetane number ranging from 75 to 85, renewable diesel combusts more readily than fossil diesel, which has a cetane number from 42 to 52. The result: better throttle response, quicker cold starts, quieter operation and less soot production. It also requires less system maintenance, thereby lowering fuel spend for fleet managers.

Renewable diesel is a direct-replacement fuel that is compatible with all diesel engines. In fact, every molecule in renewable diesel is found in fossil diesel, meaning no change in engines or refueling equipment is required to switch. Yet renewable diesel is a purer fuel, with a lower carbon footprint and better tailpipe emissions than fossil diesel. For fleets seeking a fast route to clean and efficient operations, renewable diesel has a lifecycle carbon footprint up to 80 percent lower than fossil diesel. Plus, because it doesn’t contain impurities or attract water, renewable diesel can be stored for long periods of time without any change to its properties.

Put the brakes on diesel fuel contaminants.

Don’t fill your fleets’ tanks with conventional fossil diesel, which can damage engines and fuel systems. Switch to clean fuel, like Neste MY Renewable Diesel, for a fleet that can stay in service longer with less downtime.

Matt Leuck is the renewable diesel fuel technical manager at Neste US, where he applies engine and equipment expertise to support Neste’s position at the leading edge of cleaner, low-carbon renewable fuel. Visit for more information.