Potential problems with fuel blending

Potential problems with fuel blending – Log Notes

Maurice E. Le Pera

Your November December 2003 issue contained an article that I found very interesting. The article, “Blending Used Oil and Vehicle Fuel,” gave the reader a clear description of this used oil disposal practice. The advantages of using this practice were clearly listed, but the potential problems were merely mentioned without an explanation (“Oil blending has many advantages and a few disadvantages.”).

The author mentions that this practice was approved by the Army’s Tank-automotive and Armaments Command, but recent findings have revealed a potential problem area. At the October 2003 Society of Automotive Engineers meeting in Pittsburgh, SAE Paper #2003-01-3139, Interaction Between Fuel Additive and Oil Contaminant: Field Experiences, reported that mixing engine oil with fuel can cause fuel filter plugging. The following comments were taken from the paper:

The normal range of engine oil mixing into the

fuel due to high pressure injection is less than

0.1% while the disposal mixing is generally less

than 0.5%. This practice (i.e., the disposal mixing)

has been exercised for decades without

much problem if the used oil is properly filtered.

However, recent field experiences have indicated

that interaction between engine oil components

and some acidic additives in the fuel can cause

premature fuel filter plugging. This is of immediate

concern as customers can not predict which

fuels have problematic additives.

The concern is that because filtering cannot remove the additive components or their reaction products from the engine oil, these elements will be available to react with the acidic additives that are present in some fuels, primarily the dimer-type corrosion inhibitors (MIL-PRF 25017) that are mandated in fuels such as JP8, JP5, and even some of the ground diesel fuels.

Since the author recommends that the oil-blending device be required in all maintenance activities, readers should be aware of this possible problem. One might say, “All that glitters is not necessarily gold.”

Maurice E. Le Pera

Harrisonburg, VA


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