Fuel Blends 101: What are They?

Man pumping gas

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Blends are mixtures of traditional and alternative fuels in varying percentages. Blends can be thought of as transitional fuels. The lowest-percentage blends are being marketed and introduced to work with current technologies while paving the way for future integration. For example, B5 and B20 (biodiesel) can be pumped directly into the tank of any diesel car or truck. Ethanol is also blended (about 10 percent) into much of the gasoline dispensed in the United States, especially in metropolitan areas, to reduce emissions.


It’s all part of the transition to using more alternative fuels. Although pure alcohol (ethanol or methanol) will burn independently, cold weather starting can be a problem. An engine has to be designed exclusively for a particular fuel to take advantage of all the characteristics of that fuel.

Without the infrastructure in place to support pure alcohol fuels, flex-fuel vehicles (FFVs) have been designed to run on both alcohol and gasoline. FFVs marry the best characteristics of both ethanol and gasoline (or methanol and gasoline) and make it possible to utilize higher blend percentages such as E85 (ethanol) and M85 (methanol).


  • Cleaner burning than straight gasoline: Reduced exhaust emissions.
  • Partially renewable: A portion of the fuel used can be replenished without fossil fuel reliance.


  • Corrosive: High alcohol content can be damaging to fuel systems.
  • For the higher blends such as E85, an FFV is needed.

Safety & Handling

The blends tend to be less volatile than gasoline with a reduced chance of explosions in accidents.


As transitional fuels, blends are extremely popular with excellent potential. Ethanol has captured most of the developmental resources encouraging the planning and building of new refineries for these grain-based alcohols.