Diesel Owner Tips

Diesel Fuel In the '90s

     Diesel fuel quality is declining throughout the world, and we expect this trend to continue.  In fact, a recent survey suggests that 70% of diesel fuel sold at service stations does not meet the Society of Automotive Engineers' (SAE) standard for diesel fuel lubricity.  The three leading factors affecting fuel are: 

- Crude oil sources
- Refining techniques, and
- Blending techniques


Crude Oil Sources - In the past, crude oils were selected with the end product in mind because certain crudes lend themselves to producing high quality fuels and others do not.  As crude oils become more scarce, the ability to carefully select specific crudes is less economically feasible and compromises are made.

Refining Techniques - In order to increase the amount of a certain end product that can be refined from a barrel of crude, refineries now use a process called catalytic cracking.  The process is economical and produces a high quality product for gasoline, but not for diesel fuel.  Due to the cost advantages of this process and the increased demand for gasoline, "cracking" is likely to be the preferred refining method in the future, resulting in lower quality diesel.  Another refining issue is the process used to reduce the sulfur content in diesel fuel.   (Manufacturers are required to meet lower sulfur content limits due to environmental regulations.)  The process has the side effect of reducing the lubricity of the fuel. Tip:  These fuel quality issues can be addressed by using a quality fuel additive, such as Stanadyne's Performance Formula®, which helps protect against excessive wear and corrosion while increasing both power and fuel economy.  Performance Formula also has ingredients to help prevent the fuel from gelling in cold weather.
Stanadyne Lubricity Formula is specially designed to restore optimum lubricating properties to "winter blend" and other "dry" fuels such as kerosene and Jet A.

Blending - The third factor affecting fuel quality is blending.   In cold weather conditions, for example, many refiners blend kerosene (or number 1 diesel) with number 2 diesel to lower the temperature at which the fuel starts to gel.   This has the undesirable effect of reducing the energy content of the fuel, resulting in a decrease in fuel economy.  It also may adversely effect the fuel's lubricating and performance properties resulting in potential wear on vital engine components.  In many diesel fuel injection systems, the fuel itself is the only lubricant for the precision engineered injection pump.

Basics of
Fuel Filtration

     Proper filtration of diesel fuel is critical to maintaining the performance and long life of a diesel engine.  In order to produce and control the extremely high injection pressures common in a diesel, the injection pump components and nozzles are machined to extremely close tolerances - often measured in microns (one micron is 40 millionths of an inch).  To prevent the premature failure of these vital components, it is critical that diesel fuel be filtered to remove extremely small particles of foreign matter.  The particles that a secondary or final fuel filter, for example, are in the range of 5-10 microns (.0002 - .0004"). To illustrate how small these tolerances are, consider that:

• The naked eye cannot see particles smaller than 40 microns.
• A grain of sand is approximately 100 microns.
• A human hair is approximately 70 microns.
• A single grain of talcum powder is 10 microns.

Tip:  Every diesel engine should come with a factory installed "secondary" or final fuel filter.  Often, this is the only fuel filter on the vehicle.  However, for complete protection, and especially for applications where water, dirt, and other contaminates are possible, a primary of pre-filter separator should be installed.   It should be located upstream of the existing fuel filter, betweek the fuel tank and the fuel lift pump.

Leading OEMs such as General Motors, Caterpillar, John Deere, and Perkins specify Stanadyne's Fuel Manager™ to protect their engines.  Follow their lead and fit a Fuel Manager™ filter/separator to your vehicle for additional protection.  An added benefit of the Fuel Manager™ is its modular design with see-thru water collection bowl, fuel heater, electronic water-in-fuel sensor and other options.

Water In Fuel

     The greatest enemy of diesel fuel injection components is water.  Once water enters the fuel system, it will rapidly wear and oxidize steel components and lead to:

• Rusting and corrosion of components
• Governor/metering component failure
• Sticky metering components (both pump and nozzle)
• Injection component wear and seizure


Tip:  Free or emulsified water must be removed from the fuel to prevent corrosion and damage to the fuel system.  The best way to do this is with a Stanadyne Fuel Manager filter incorporating a water separator.  Be wary of certain additives which claim to "remove water." In fact, they dissolve the water, which eventually will pass through the filter and attack the injection components.  Stanadyne additives demulsify the water, pulling it out of solution so the filter/water separator can more effectively remove it.

Water contamination can exist in diesel fuel in three forms:

1) Emulsified water, where the water is suspended in the fuel like oil and vinegar in salad dressing.

2) Free water, where the water is separated from the fuel and usually is found on the bottom of fuel/storage tanks.

3) Dissolved water, where the water has been chemically dissolved in the fuel, like sugar in coffee.  The warmer the fuel, the more water will be dissolved, but as temperatures drop, the water will come out of the solution in the form of free water.