How to Clean Waste Oil

Updated April 17, 2017

Cleaning waste oil for reuse or recycling requires filtering out suspended particles. Filtering waste oil has the advantage of reducing oil consumption and is a vital pre-treatment step for oil recycling. Any oil can be filtered using this process, including cooking and motor oil. Many are not aware that used oil can be reused. Applications for oil reuse include cooking, oil changes and general lubrication purposes. Recycling oil is an activity that respects the limits of our non-renewable resources. Learning how to recycle your used oil is simple and could even help save the environment.

Place the used oil jug on a shelf above the destination jug. Gravity will pull the liquid downward along the natural-fibre rope in a process known as capillary action, thus filtering out suspended particles. Since a rope is naturally dry, it will create capillary action to absorb the liquid oil, in much the same way a paper towel absorbs a wet spill.

Place one end of the rope into the used oil and the other end into the recycled oil container. Make sure that the rope does not touch the side of the jugs and that it is completely submerged in the oil. This is important since contact with the jug can disrupt capillary action. The rope should go straight out of the top jug and then make an upside down "U" shape. The rope is inserted straight into the bottom jug. Capillary action should begin to draw the oil from the used oil container to the recycled oil container.

Wait several weeks. To prevent contamination from dust in the air, it's necessary to cover the containers and rope with a sheet of plastic.

If filtering used motor oil, add 1 qt. of new motor oil for every 3 qt. of recycled oil. This is necessary to replace detergent and anti-foam ingredients that prevent engine sludge. According to Nordic Group, "These oils have additives to reduce wear (especially at start-up), maintain viscosity and to suspend the soot and contaminants (by-products of combustion) that they wash off the interior engine parts."

Once the rope has finished filtering oil, it can either be discarded or reused. In the case of cooking oil, all suspended particles will have been filtered by the rope, making it suitable for reuse in cooking.


The farther the oil has to travel through the rope the longer it will take to obtain recycled oil. Avoid the temptation to check the progress of the oil filtration. Exposing the oil to dust in the air can ruin the oil's quality.


Oil and rope are both flammable materials. Keep them away from flame. Never use the same rope to filter vegetable oil and motor oil. Motor oil is toxic and should never be ingested.

Things You'll Need

  • Natural-fibre rope
  • Used oil
  • 2 large glass jugs
  • Sheet of plastic or tarp
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About the Author

Samuel Sohlden began his freelance writing career in 2007. His work appears on various websites, with articles focusing on science and health. In 2010 he attended the Intel International Science and Engineering Fair in San Jose, Calif. Sohlden is pursuing a Bachelor of Science in microbiology from the University of Cincinnati.