Improve Your Fleet Fuel Quality

A major percentage of all problems with diesel fuel engines are related to fuel quality. Diesel fuel can sometimes vary from one shipment to another or from one area to another. Customers also switch from one fleet fueling vendor to another and suppliers sometimes change the fuel they are offering. The three things that vary the most in diesel fuel are cetane, weight and viscosity. Cetane is defined as the susceptibility of the fuel to self ignite. Cetane can influence both starting and combustion roughness of an engine.

The weight of the fuel or specific gravity plays a major role in the heat content of the fuel. Number 1 is a “lighter” grade while number 2 is “heavier” or weighs more per gallon. While the lighter fuel (#1) has a lower “cloud point” and may provide better starting in cold temperatures, the heavier fuel (#2) has better lubricating qualities and actually contains more heat units (BTU’s) per volume. Assuming the fuels are the same price, better fuel economy is obtained by using #2.

The third aspect of fuel to consider is viscosity. Since “lighter” (#1) fuel is less dense it becomes thinner when heated than the heavier #2 fuel. When this occurs more fuel begins to leak through the high pressure parts of the injection pump which actually causes the injection pump to pump less fuel. As the fuel temperature continues to increase, more fuel is lost through leakage and this results in a power loss of between 1% and 7%.

Taking all these things into consideration #2 diesel fuel is the best all around fuel for the diesel engine. Buying fuel from a reputable dealer is a good way to insure high quality fuel. The best ones seem to be places that move a lot of diesel fuel such as truck stops, etc. The only way to insure your fuel quality is to treat it yourself with a diesel fuel additives and since every tank may be different every tank will need to be treated. For more information on diesel fuel additives programs and fuel savings contact Sokolis Group at 267-482-6155 or on the web at and let us work together on your fleet management system.