Anuj Kumar
Senior Project Manager
How re-refined base oils (RRBOs) are climbing the API ladder, filling the viscosity gap, and entering markets that were hard to imagine until recently.
For much of their history, RRBOs have carried a slightly apologetic label in the lubricants industry. They were seen as an honest, sustainable alternative, but one that could only do so much. The general assumption was that RRBOs would remain a Group I and Group II story, useful for a defined set of applications, and that anything more premium, or anything heavier, was best left to virgin refiners. That assumption is now steadily coming undone.
The last few years have witnessed RRBOs moving up the API ladder and simultaneously widening the range of viscosity grades and end uses that they can address. What was once a narrow slice of the market is quietly becoming a broader participant. The industry is still small in absolute terms, but the direction of travel is unmistakable.
Climbing the API Ladder
Not too long ago, a re-refiner producing Group II was itself considered a leap. Then came Group II+, and now Group III is being produced from used oil on a commercial scale.
Germany’s Puraglobe is one of the most cited examples. Its HyLube and HyRes technologies have allowed it to run process trains producing Group III and Group III+ base oils that are molecularly comparable to virgin premium grades.
In North America, Safety-Kleen, a Clean Harbors company, has been steadily lifting the share of Group III in its output mix, alongside its established Group II+ KLEEN+ product. With production operations in Europe and the U.S., Avista Oil claims the capability to produce some amount of Group III base oil at its re-refineries in Germany and the U.S.
If RRBO can play in marine cylinder oils, the argument that it is only fit for “less critical” uses becomes harder to sustain."
The performance conversation has also shifted. Blenders that have evaluated these products head-to-head often note that a well-produced RRBO can match a virgin equivalent on the datasheet, and in a few parameters actually exceed it. It is a very different starting point from the one that the industry began with more than a decade ago.
The Naphthenic Story That is Rarely Told
While much of the recent excitement centers on paraffinic Group III, it is worth noting that re-refining has quietly served a premium segment for decades. Used transformer oils have long been collected, re-refined, and returned to the market as naphthenic base oils, often finding their way back into transformer oil formulations. It is one of the older circular loops in the industry, running well before the word “circularity” became fashionable. The fact that it happens without much noise is itself a sign of how normal the practice has become.
Filling the Viscosity Gap
The other historical limitation of RRBOs was viscosity. Re-refiners were comfortable producing light and mid neutrals, but heavier grades were considered structurally difficult, partly because of the nature of used oil feed and partly because of the yield economics at the back end of the process.
That gap is now being addressed. Clean Harbors has announced plans to build a unit within its Safety-Kleen re-refining system that will convert its vacuum tower asphalt extender byproduct into a Group II N600 heavy neutral, with commercial start-up targeted for 2028. It will be the first re-refined 600N produced in the United States, and if it delivers on specification, it opens up industrial and heavy-duty engine oil formulations that had so far been out of reach for RRBO.
The quality of the infrastructure around used oil collection is a determining factor on the quality of the rerefined product.
Separately, a few technology providers are now claiming that their process configurations can also yield re-refined brightstocks, a grade that until recently was considered almost impossible for a re-refiner to produce. If any of these claims translate into commercial output over the next few years, the “viscosity gap” argument against RRBO will lose most of its remaining ground.
Beyond Automotive: The Marine Frontier
The other frontier is application. RRBOs were long treated as a solution for passenger car motor oils, some industrial fluids, and a limited set of specialties. That is now changing. In one of the more interesting recent developments, Avista Oil worked with a leading Danish shipping company to co-develop a reduced viscosity marine cylinder lubricant that uses RRBO as a major component of the base oil blend.
The product not only cut the carbon footprint of the cylinder oil by a meaningful margin, but it also delivered a small but measurable reduction in vessel fuel consumption. Marine cylinder oils are a highly demanding application.
If RRBO can play there, the argument that it is only fit for “less critical” uses becomes harder to sustain.
Why This Matters
Put together, three shifts are visible:
- RRBOs are climbing the API Group ladder
- They are widening their viscosity coverage
- They are entering application segments that were considered off-limits
None of this makes them an overnight replacement for virgin base oils. Global RRBO output still accounts for a small share of total lubricant demand, and feedstock quality, collection infrastructure, and financing remain real constraints. However, the ceiling on what RRBOs can do has moved up meaningfully, and it continues to move.
For basestock producers, additive companies, lubricant blenders, and financiers, the practical question is no longer whether RRBOs will matter. It is where RRBOs will matter in their portfolio and by when they will need to plan for them.
