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The problem with diesel – Part 3

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World Coal,

In the first two parts of this article, Michael Holloway, Certified Laboratories, US, discussed the problems presented by and the effects of using ultra-low diesel fuel in heavy-duty diesel engine. The article concludes by looking at use of biodiesel as an alternative diesel fuel and the benefits of using a fuel treatment programme.

Bio-based biodiesel
Biodiesel is an alternative diesel fuel produced from a renewable resource – typically soybean oil (soy oil methyl ester), rapeseed oil, palm oil or animal fat. Biodiesel contains no petroleum but it can be blended with petroleum to create a biodiesel blend. The typical blend is 20% bio-based fuel and 80% diesel fuel and is known as B20 diesel fuel. Several states have passed legislation that subsidises the use of this fuel to make it more affordable and to support farmers. In 2006, approximately 100 million gallons of biodiesel were sold, a 35% increase from 2005.

Biodiesel provides the following benefits:

  • It is produced from a renewable domestic resource, which reduces our reliance on imported oil.
  • It provides higher cetane fuel.
  • It has increased lubricity.
  • These benefits can help when blended with ULSD fuel. The increased lubricity of biodiesel will offset the lack of lubricity of ULSD. The improvement in cetane will also help in a cold start.

However, biodiesel also has the following problems:

  • Very poor low temperature characteristics: trace glycerin will quickly form solids and precipitate clogging filters and restricting fuel flow.
  • It is very susceptible to degradation from water: it has a greater ability to emulsify with water.
  • It is highly susceptible to bacteria degradation: a lack of sulfur and a rich hydrocarbon environment make it perfect to grow various forms of bacteria and fungus that will reduce the cetane, increase acidity from the microbe’s by-products and clog lines, filters and injectors.
  • Poor oxidation resistance: the ester molecule on the hydrocarbon chain makes the fuel very susceptible to oxidation which lowers the overall ability of the fuel to combust.
  • There is a big difference in the cold flow properties of different types of biodiesel (for example with origins of rapeseed vs. soy, or tallow vs. palm), as well as the various batches of ULSD. Some batches can have a 40ºF difference in the gel point temperature. Work is underway to lower the gel point.

Finding a solution
The solution to the problem is to use a fuel treatment designed for increased fuel performance. One such product/programme that has been found to be successful at correcting the issue is the fuel quality assurance programme implemented by Certified Laboratories. This programme includes adding to the diesel fuel a product known as Diesel-Mate All Seasons®. Customers have reported an increase in engine performance and a reduction in failed injectors. The fuel improver is a multi-functional diesel fuel improver designed to:

  • Boost cetane.
  • Reduce emissions and carbon footprint.
  • Reduce friction and wear.
  • Separate out water.
  • Clean injectors and pumps.
  • Prevent fuel gelling (without the use of alcohol).
  • Reduce oxidation during storage.
  • Prevent rust and corrosion.
  • Contain metal deactivators.

It should be noted that the use of the improver may also improve fuel economy slightly. However, there has been a recent increase in the number of claims regarding fuel economy when using fuel additives. While a cleaner engine, which is free of deposits, will perform at near to optimum levels, it is important for users to beware of any company or product claiming an improvement in fuel economy. The fact of the matter is there is absolutely no way to guarantee an improvement in fuel economy in any given engine. There are far too many variables that influence fuel economy, and statements offering a vast improvement in fuel economy should be viewed with scepticism.

Written by Michael Holloway, Certified Laboratories, US.

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