This the first of three articles in a series about re-refined base oil’s place in the passenger car and heavy-duty vehicle market.

Re-refined base oil (RRBO) is a concept that goes back decades and is continuing to evolve. It is produced through processes that remove lubricants, water, debris and other impurities from used oil. While it is not possible to produce a base oil from used engine oil that is as pure as virgin base oil, modern refining processes have been able to develop re-refined base oils that get closer to the level of purity needed to meet at least some OEM specifications. Most often, RRBO is mixed with virgin base oil to produce a quality product that reduces the reliance on virgin base oils.

Just as technology and processes have improved to deliver a better RRBO product, demand for and curiosity about the possibilities of RRBO have grown. The viability of RRBO as an alternative to virgin base oil is good news for those who want a reusable product. And new research has shown a real advantage to using RRBO versus virgin base oil from the standpoint of CO2 emissions.

Positives for RRBO: Addressing disposal challenges while reducing CO2 emissions

RRBO is one way of addressing the issue of what to do with the millions of litres of used engine oil that are dumped irresponsibly into storm sewers, drains, or into the ground. When engine oil is collected for disposal in a responsible manner, the disposal method most often used – combustion – is not an environmentally friendly measure. Companies that collect used engine oil from manufacturers, dealerships and quick lube businesses to be processed for RRBO are taking the used engine oil out of the waste stream.

Additionally, according to study released by GEIR (UEIL) in 2022, Updated Life Cycle Assessment for Regeneration of Waste Oil to Base Oil, re-refined base oils have a lower carbon footprint compared to virgin base oil production processes, with a lower output of CO2 emissions of up to 71 percent compared to virgin products.

With new understanding of the advantages of RRBO, some countries have started to set targets for the collection and recycling of used oil, with others around the world expected to follow. Turkey requires base oils to be made up of 12 percent re-refined in 2023, growing to a requirement of 15 percent RRBO in base oils in 2024.

Still, some hurdles to adoption exist.

Challenges: Refining processes, availability and quantity

No single process exists to produce RRBO, but solvent extraction is commonly used. Typical steps in the solvent extraction method are:

• Dehydration to remove water and moisture.
• Heating to remove light fractions.
• Solvent extraction to remove contaminants.
• Hydro-treatment, to force a molecular conversion.

Other processes call for other techniques, but all forms of producing re-refining base oil are complex and can be costly. The collection of used engine oil itself requires a network of operators to coordinate distribution of the raw material for refining. Virgin base oils require processing, too, of course, but the process for producing RRBO requires the removal of various polymers, zinc dithiophosphates and other additives.

Another challenge for a market seemingly open to using RRBO is that even with millions of litres of used engine oil out there globally, the amount that gets produced as a RRBO currently is not enough to support the needs of the market.

Applications for RRBO

RRBO can be processed to a quality level that is closer each year to virgin base oil, but, for now, using RRBO as a portion of a base oil is seen as the most practical way to cut back on the amount of virgin base oils needed while still delivering a product that meets OEM standards.

The bottom line is that interest in and adoption of re-refined base oils is growing and the use of RRBO is expected to increase in the future as availability improves. 

Next in the series: Understanding Extraction and Other Processing Steps in Re-Refined Base Oil Production