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What Is No. 1 Diesel Fuel?

by Chandra Anderson

Diesel fuels come in differing grades, each with specific properties for specific applications. Diesel fuels are rated No. 1, 2 or 4 with No. 1 and No. 2 used most often in cars and trucks and No. 4 in locomotive engines. Marine diesel fuels are identified by letter designation such as DMA or DMX.


No. 1 diesel fuel is considered a light-middle grade fuel for use in abnormally low temperature conditions and with speeds and loads which vary widely.


No. 1 diesel has a low volatility, or vaporizing, point. In general, all diesel fuels have lower flash points than gasoline and are inherently safer. No. 1 diesel fuel distills at a lower flash point than No. 2 or No.4, providing more reliable engine performance in lower temperatures.


The American Society for Testing and Materials (ASTM) sets the standards for diesel fuel quality and emissions. The standard ASTM D 975 specifically states the amount of emissions an engine running on No. 1 diesel is allowed. Sulfur is the main concern in diesel emissions and the standard allows for no more than 5,000 parts per million vented to the atmosphere.

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