Heating oil sludge is a common name for deposits of impurities found at the bottom of your oil tank. Hard to notice, as it lies deep in the oil tank, sludge represents a multitude of various impurity particles which came along with many deliveries of heating oil. Fuel oil is relatively lightweight and most impurities it may be carrying are heavier. This all makes these particles drop to the bottom and build up over time.

Water can be even more dangerous.  Most of the water in the tank comes from condensation, which is a result of difference in temperatures inside and outside the tank. As water is also heavier than oil, it will collect on the tank’s bottom. Water deposits represent a good place for growing various bacteria, and these bacteria release acid which may lead to tank corrosion. And corrosion means oil leaks.

Water can also be found in low quality oil, though quality control now is very high and amount of wateroil tank sludge in your oil is very low, but it still may be present in small amounts.

Oil sludge can comprise of various solid particles, most often ashes, but sometimes also minerals and metals. It is common that oil from the bottom of a barge or a wholesale inventory tank has more impurities. That is why this oil is usually sold at a lower price to the end consumer. Some suppliers, however, can be dishonest and sell you that oil at a regular price without your knowledge, knowing you’re not able to spot these impurities and their concentration.

Don’t let the oil in your tank run out! When that happens all the sludge from the bottom of your tank would end up clogging your filters and you’ll most likely need a burner service to change the oil filters and clean up your furnace.

Here are some suggestions to help deal with fuel oil sludge

  1. Use oil sludge treatment. Hardware stores sell chemicals called Fuel Oil Sludge Treatment which disperse the sludge by breaking down particles, killing bacteria from deposed water which produce acid and emulsify the oil. These chemicals need to be added anytime you fill your tank. Some suppliers always add sludge-preventing additives to their oil.
  2. Clean your tank. When the season ends, you can find a waste oil contractor to thoroughly clean off the bottom of your oil tank. Do not try to use the oil from the bottom, as burner problems may occur due to high concentration of particles.
  3. Move your oil tank indoors. Besides other advantages, indoor tanks produce less water condensation, as they are not exposed to sharp daily temperature changes.
  4. Buy oil from reputable suppliers. Some dishonest “discount suppliers” actually buy oil from the barge bottom from wholesalers and even other retail suppliers overnight, to resell it quickly as regular oil. Make sure that a supplier of your choice can confirm the origin of their oil, and buy from suppliers who only buy their oil directly from the terminal.
  5. If your tank has corroded, replace it. Buying a new tank is not only a more reliable solution, it is also often cheaper than any attempt to fix an old, rusty tank. A new tank will provide you with years of reliable service if maintained properly.