Despite being one of the top two expenses of running a transport business, the diesel that goes into the tank is taken for granted by most operators. As long as it meets EN 590, diesel is diesel, right?

Not quite, as Emma Wyatt, Shell fuels scientist, explains. “There are something like 10,000 different hydrocarbon components in a base diesel,” she says. “But there is a big difference in the performance of fuels, especially for heavy duty vehicles, depending on the additive package.”

Wyatt joined Shell in 2007 after completing a PhD in organic chemistry at Cambridge University. She is based in Shell’s Bank Street offices in London, but Shell’s main labs these days are in Hamburg, Germany. One of her key roles is to manage the development of Shell’s FuelSave diesel, which was launched in 2009 and is now available in 23 countries. Her challenge is to develop a fuel that will suit cars, vans and heavy trucks.

“We have to have a product that works for all those customers,” she says. “The amount of work a heavy duty vehicle is doing is huge compared to my car that goes out a few times a week. So understanding the requirements of heavy trucks is an important part of the work we do.”


One key component that all diesel engines have in common is the injector, and Wyatt is constantly searching for a fuel that is kind to these hardworking parts while still burning efficiently in the engine.

“A large amount of the work we do looks at how these injectors are working and how our fuel formulations are interacting,” she explains. “The holes through which the fuel has to flow are about the width of a human hair so if you get deposits forming inside those holes that has a major effect on the way the engine is operating.

“The main driver is developing additives that keep the injectors clean and make sure the vehicle is operating at its optimum performance for as long as possible.”

Apart from carbon build up, a recently discovered phenomenon called internal diesel injector deposits (IDID) is giving fuel companies a few headaches.

“We have known about traditional injector deposits like soot for a long time but IDID is a relatively new area,” says Wyatt. “There are a number of theories about what is causing these and it is a big area of research across the whole industry.”

One proposed solution is to put special additives in the vehicle tank to combat IDID but Wyatt is confident that Shell FuelSave contains all the additives necessary straight from the pump.

“We recommend using a fuel like FuelSave contains a low level of the additives all the time to prevent these deposits forming in the first place,” she says, “rather than these very high detergent concentrates you can buy. The analogy I use is that just adding more and more washing up liquid to your washing up bowl won’t get your plates cleaner, it just creates more foam that you don’t need. These concentrates can be quite aggressive and we recommend a continual low level of additive.”


Another key development has been the arrival of Euro-6, bringing an increased prevalence of SCR exhaust after treatment, which every truck manufacturer is now using with or without EGR, and higher injection pressures.

“This alters the way vehicles work and might alter the way our fuels interact with them,” says Wyatt. “But Shell FuelSave hasn’t changed dramatically between Euro-5 and Euro-6. We were bench testing a Euro-6 engine for a number of years in the run up to Euro-6 and we didn’t need to make major changes. We have tested it extensively and are confident it still works. We work closely with the manufacturers to make sure we are never surprised by new technology.”

While FuelSave undoubtedly costs more than a base diesel without additives, test have shown that 3% better fuel consumption is possible over the lifetime of the truck. “We have tested FuelSave in a wide variety of operations and in some cases the benefit was even bigger than 3%,” says Wyatt. “Most of that is coming from keeping the injectors clean so it is a long term comparison. Running a new vehicle from day one on FuelSave will maintain the optimum performance of the engine for its lifetime.

“If you buy a secondhand high mileage vehicle and use base diesel its performance will continue to deteriorate. If you put in FuelSave its performance will be maintained at the point at which you bought it.”


The UK is proposing to increase the percentage of biodiesel that must be used in transport fuel from 7% to 10%, and Shell is working to ensure its additive package will be suitable for this higher renewable fuel content.

Wyatt says: “Biodiesel is very easy because it is a replacement for part of the diesel fuel without the need to modify engines. There is definitely a conflict where the biodiesel is sourced from crops and Shell has programmes ensuring that biodiesel is coming from sustainable sources. We want to move away from crop-based diesel to explore future alternative biodiesel sources. We expect biodiesel to remain a part of the liquid fuel supply chain for many years.”

Looking ahead to the next generation of low carbon emissions diesel engines, Wyatt says little is yet known about the shape of future legislation.

“It is quite early stages in understanding what that technology means,” she says. “We are working with engine manufacturers to hear what they are doing to meet Euro-7. They don’t have the answer instantaneously and we have to work with them to understand what the differences means for the fuel. We will be testing the new engines before they are available and if necessary adjusting the formulation of the fuel.”