By doing this it is easy to see how cost savings can be made and how a better fuel consumption rate (miles per gallon, or mpg) will give you an overall cheaper diesel fuel cost.

One of the very important points to acknoweldge is that a well maintained, smooth running engine is about the most important factor in achieving better fuel economy. Fuel quality is probably the biggest causes of problems with diesel engines, and these can occur in several ways.

1. It can vary from shipment to shipment

Even if you use the same vendor each time you fill up with diesel, there can be changes in the fuel they are providing. The diesel quality can change, even in a small way, with each shipment your vendor receives. The key variables are:

* Cetane: this is the level at which the fuel will self ignite, with acceptable levels being between 40 and 45. Because the levels can change with every delivery, the are not widely known. The starting and combustion roughness of your engin can be affected by the cetane level.

* The 'weight' or specific gravity of the diesel will affect the fuel's heat content. Lighter fuels (Type 1) have a lower cloud point and is generally regarded as better in colder temperatures. The heavier diesel (Type 2) has good lubricating qualities, and if they are both the same price, the heavier fuel generally gives better fuel economy.

* The viscosity of the fuel governs the efficiency at which fuel travels through the high pressure parts of the injection pump. Type 1 will reduce your fuel economy because it tends to have more fuel leakage.

Purchasing your diesel from truck stops is generally regarded as the best way to ensure you are buying a quality product. These retailers would go out of business fast if they began to supply inferior fuel.

2. Using a fuel reformulator

After millions of miles of road tests around the world, there can be no doubt that using a fuel reformulator will reward you with better fuel economy resulting in cheaper diesel fuel costs.

These reformulators, like Ethos FR, should not be confused with 'fuel additives' - the type sold in automotive retailers. These are alcohol or gasoline based products that actually increase your fuel costs because of the quantity you need to add to each tank.

The main reason for treating diesel is to provide better lubrication, to ensure all the desired working parts of the engine are lubricated, running smoothly. Many drivers don't realise that since low sulfur fuel was able to be used on road vehicles, the life expectancy of the fuel injection system has dropped by up to 25%.

The lubricating and cleaning esters in this fuel reformulator are show-stopping technology in action. Its use results in fuel burning more completely, and gives an appreciable net gain in mileage per gallon - meaning cheaper diesel costs overall.