What is “bad” fuel?

Written by Capt. Jeff Werner

Fuel is made to certain ASTM specifications. When it does not meet these specs, we could refer to it as “bad fuel”. However, we tend to refer to fuel as “bad fuel” when we see symptoms such as:

  • Dark, hazy fuel
  • Filter clogging
  • Sludge build up in tanks
  • Poor engine performance
  • Excessive smoke and emissions

We refer to fuel and “good fuel” when it is clear and bright. Or rather in that case, no reference is made at all to our fuel. We simply use it and take fuel quality and peak engine performance for granted. Bad fuel is fuel that does not meet ASTM specifications.

Capt. Jeff Werner, a Licensed USCG Master, has sailed professionally throughout the world. ┬áHe is also the Diesel Doctor, helping to keep your boat’s fuel clean and bright.