Southern Illinois University Waste Oil Recycling Project

Looking to use Waste Motor Oil in a diesel vehicle? Then you’ll love this awesome project that the folks in the Automotive Technology Department at Southern Illinois University Carbondale did!

They wanted to see if it was possible to convert Waste Motor Oil into a fuel that could be used in a diesel engine.

The major goal of the project was “to repurpose a waste product into a usable commodity”. So, they wrote up a project plan and submitted it to the Sustainability Green Fund at the college, received funding for the project and the fun began!

During their project they were able to repurpose over 900 gallons of used motor oil! (that’s a lot of oil!) The normal disposal cost of this oil is $0.85/gal, so by diverting it to another purpose they were able to realize a savings of $765 in waste disposal fees!

To start the project off, they purchased pallet racks, spill pallets, and decking to build a processing station to clean the waste motor oil and also purchased one of our Extreme Raw Power Centrifuge Units to purify the oil before it’s use. They also purchased one of our Goldstream Monster Gear Pumps to move the oil around along with several tanks and other supplies needed to get them set up and going.

They identified an area on campus to set it all up, epoxy coated the floor (because waste motor oil is MESSY!!!), and then began assembling everything they’d need to perform the project.


Then the fun started! They collected oil from the University Automotive Department and also from the Flight Services department (Used oil from aviation engines–pretty cool!)


Students from the Alternative Fueled Vehicles and Special Projects classes were heavily involved in the project and the project itself was overseen by Blaine Heisner, an Associate Professor at the University.

As of this writing (April 2018), the project is still ongoing so the findings aren’t in, but here’s how things are rolling.

Once they’ve collected the oil they begin to filter it using the centrifuge. The oil passed through a 10 micron fuel filter first, then into the centrifuge for fine filtering.

Once filtered it goes into their large storage tanks where they have a 2 micron fuel filter mounted just before the pump dispensing nozzle

Some of their findings are pretty cool too! (they’ve discovered lead in the Aviation Oil that the centrifuge isn’t completely removing).

Here’s some details from the project:
This is from the centrifuge testing they’re performing
3 tests performed in order to determine optimal centrifuge supply valve position for desired flow rates
(Target flow rate minimum 10gph maximum 25gph)
– Oil was heated to approx. 150°F
– Oil was collected at the silicon hose post-heating element to simulate real time supply flow rates
– Flow rates were determined by filling a quart container and scaling up from quarts/minute to gallons/hour accordingly
– 1st test flowed approx. 60gph
– 2nd test flowed approx. 15gph
– 3rd test flowed approx. 20gph (valve was marked)

NOTE: The original reason for desired supply flow rates within the range of 10gph and 25gph is that the advertised maximum capacity for our centrifuge to efficiently clean oil was 25 gph with the cone attachment and ABB 3-phase 240V driver. Furthermore the minimum flow rate recommended by Utah Biodiesel was 10gph, boasting filtration down to 1 micron. What I have realized is that no matter what is advertised, the slower the oil is run through the centrifuge, the cleaner it will be.

EDIT: We love this observation! It’s so true! While any centrifuge will do a good job, the slower you run the oil through it, the more filtered it will become. – Utah Biodiesel Supply

NOTE: After much observation and testing of the centrifuge, I have concluded that the best way to gauge whether or not the centrifuge is operating within its capacity is to pay close attention to the clear sump/overflow hose. The only two reasons any oil will leave the centrifuge via this hose is if the supply flow rate is more than the centrifuge bowl can hold or if the centrifuge is no longer spinning and the oil which was suspended in the bowl by centrifugal force has been allowed to run out of the bottom drain holes in the bowl.

NOTE: There is no reason not to turn the heating element to the maximum setting of 250°F. The extra heat from the element can only aid the oil cleaning process because thinning the oil via heat while being centrifuged makes it easier for all particles which are heavier than motor oil to fall out of suspension. Furthermore the hotter the element is the more likely it is to remove all moisture from the oil. When the oil is leaving the centrifuge with the heating element set at 250°F, water vapors can be observed leaving the clear hose which is an indicator that moisture is in fact being removed

After it’s filtered, the waste motor oil is then blended with stale gasoline, old diesel fuel, and mixtures of both to thin down the filtered waste motor oil to the the viscosity of diesel fuel

Here’s how they’re performing their Viscosity testing along with some of their notes:

Materials Needed
100mL Graduated Cylinder (Plastic)
1/8” Drill Bit
Drill or Drill Press
Small container for fuel collection

– Turn graduated cylinder upside down and drill a hole using a 1/8” drill bit as close to dead center as possible
– Be sure to drill as straight as possible and quickly remove the drill bit after the hole is made, the drill be should pass through the hole with zero lash when done
– If necessary, remove all plastic burrs from the hole that was just drilled
Viscosity Test
– Fill graduated cylinder to 100mL mark
– Be sure to cover the hole in the bottom of the graduated cylinder with either a finger or a small plug
– Using a stop watch, begin recording time and remove the finger or plug from the bottom of the graduated cylinder simultaneously
– Record the amount of time it takes to drain from 100mL to 40mL in the graduated cylinder
– Repeat this test 3x and record the average
– The average of the three times will serve as a quantitative value for determining the WMO fuel viscosity relative to pump Diesel fuel

NOTE: The reason for only draining to 40mL from 100mL is that after 40mL, the fuel in the graduated cylinder does not have enough pressure on it to push the fuel out of the 1/8” hole so values have diminishing returns and do not necessarily differ from pump Diesel to WMO blended fuels. In order to see a more accurate difference in viscosities the amount of fuel which is actually drained from the cylinder can be lessened and the frequency of testing before taking an average can be increased.

NOTE: Because this test is relative to the viscosity of pump Diesel, this test can easily be scaled up from a 100mL cylinder with a 1/8” hole to a 1000mL with a larger diameter hole as desired or as allowed by materials on hand. The concept remains the same, as long as a baseline is acquired by running viscosity tests on pump Diesel the final WMO fuel product can be compared to it.

NOTE: Temperature of the fuel during testing must be taken into consideration. In my case, fleet storage is a climate controlled environment which generally stays around 70°F. Because of this constant temperature inside the building which all processing and testing took place, I was comfortable with concluding that all relative viscosity tests performed within that space were accurate.

Here’s where the projects at so far:
During the Spring Semester of 2018, completion of the processor and scaffold was complete. The centrifuge was tested and used to filter all previously collected used motor oil. Testing was performed to determine desired viscosity and cleanliness of the final product. A sample of the centrifuged oil was sent to Blackstone Labs for testing and was determined to require additional filtering processes. Research was expended and a plan to further thin the used motor oil with lighter petroleum fractions was made. Multiple batches of fuel were made to test the performance characteristics in live vehicles. At this time, the project is in the testing phase and over 100 gallons of motor oil based fuel have been successfully utilized in live vehicles. As of yet no University vehicles have been fueled with our product, but we are very close to this step. The project has collected well over 900 gallons of used motor oil from the University, individual students, and faculty, providing a responsible option to recycle this oil and keep it out of the environment. Additionally, at $0.85 per gallon in disposal fees, the project has saved approximately $765 in disposal fees.

From this point forward, we are continuing to collect used motor oil from SIUC Automotive Technology. We have discontinued collecting oil from Flight Services due to the discovery of very high levels of lead in their oil. Blackstone Labs concurred with our suspicion this level of lead is consistent with the use of leaded fuel in reciprocating aviation engines. We may still utilize agreements with SIUC Travel Services to participate in our project and collect additional oil from them as the project grows. We plan to continue to enable students and faculty to drop off used motor oil from personal use as a method of recycling their oil.

We will continue to test the performance characteristics of the fuel in live vehicles, then transition the usage into University vehicles. This transition will increase cost savings to the University in not only reduced disposal fees, but reduced fuel costs as well. SIUC Farms were contacted in regards to using the manufactured fuel and they have agreed to take 55 gallons of fuel to use in their agriculture equipment. As soon as we have completed our performance testing, we will provide our fuel the Farms for this purpose. We hope to encourage additional streams of usage for our fuel within the University, provided all testing is positive. We foresee continued successful collaboration between departments/segments of SIUC with our project for many years.

We think the project is awesome! It also illustrates some of the issues that you can run into when working with waste motor oil (ie. there’s a lot of unknown stuff that can be in it). We’ll be curious to see how they eliminate the lead out of the aviation oil too (it tends to be in liquefied form–difficult to centrifuge out).

As the project continues we’ll share their findings here.

Happy Filtering!

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