Lubricants impact the environment at all stages of production, usage and disposal. The awareness and concern over their impact on the environment has many state, federal and international regulatory bodies reviewing current policy, with some agencies beginning to enact new regulations. For example, under the Clean Water Act, the Environmental Protection Agency (EPA) recently modified the Vessel General Permit to include legislation requiring the use of environmentally acceptable lubricants (EALs) in ships navigating U.S. waters. Impending global regulations such as these have led many lubricant manufacturers to seek environmentally acceptable alternatives that also meet the rigorous performance demands of industry.
With these strict regulatory and performance requirements in mind, many of the world’s largest lubricant companies have devoted significant resources to formulating products using a new class of synthetic base oils known as estolides. Estolides are manufactured using a patented technology that converts vegetable oils into high-performance biosynthetic base oils, offering a biobased solution for applications within the automotive, industrial and marine industries.
Current performance data indicate that estolides demonstrate exceptional results in the areas of oxidative stability, hydrolytic stability, volatility, biodegradability and renewable carbon content.
Estolides offer greater resistance to oxidation and demonstrate excellent response to antioxidant additives, leading to increased oil longevity and extended drain intervals. As shown below, estolides outperform many high performance base oils currently available on the market.
Estolides exhibit low volatility, resulting in increased flash and fire points and lower evaporative loss (NOACK) as compared to other high performance base stocks. High flash and fire points make estolides ideal for applications where operating temperatures are high and flammability is a concern.
Figure 3. NOACK (Evaporative Loss) base oil comparison (ASTM D5800).
Estolides have higher viscosity indices (VI) than nearly any other base oil in industry – with high VI offering a number of advantages. Higher VI base oils provide increased film thickness at elevated temperatures, resulting in better protection, and potentially lower wear. At lower temperatures, high VI base fluids reduce viscous drag on moving parts, leading to higher horsepower and increased energy efficiency. The naturally high VI of estolide base oils also provides benefits to formulators, requiring lower treats of viscosity modifier additives to meet VI specifications.
Figure 4. Comparison of typical base oil Viscosity Indices (ASTM D2270).
BT’s estolides are fully miscible with Group I-V base oils. Additionally, unlike some synthetic base stocks, estolides are readily soluble with a broad range of lubricant additives.
While maintaining excellent stability in rigorous lubricating environments, BT’s estolide products biodegrade quickly once released into the environment. As shown in Figure 7, estolide base oils are Ultimately Biodegradable per OECD 301. Additionally, as illustrated in Figure 8, estolide-based motor oil formulations biodegrade much faster than conventional Group II motor oils.
Figure 5. Biodegradability of Biosynthetic SE7B (OECD 301).
Figure 6. Biodegradability of Biosynthetic SE7B vs. Conventional Motor Oils (OECD 301B).
BT’s estolide products have the highest Percent Renewable Carbon (PRC) content of any comparable high-performance base oil in industry.
Table 2. Percent Renewable Carbon (PRC) of common base oils.
Percent Renewable Carbon
Low Viscosity (5-9 cSt, 100C)
High Viscosity (17-40 cSt, 100C)
|Group IV, PAO|
0 – 30
0 – 75*
0 – 10
|* Typically < 50%|
Per the EPAs definition and according to OECD 117, estolides do not accumulate in living organisms.
With regulatory requirements increasing by the year, lubricant formulators have struggled to strike an acceptable balance between performance and environmental favorability. Estolide base oils offer an innovative tool for such formulators, bridging this gap by offering a high-performing, biodegradable and renewable alternative to traditional synthetic fluids.
Through extensive testing with some of the world’s largest manufacturers of automotive and industrial lubricants, estolides will become a key component to fully certified, biosynthetic lubricant formulations. Estolides cast aside past perceptions that products derived from vegetable oils are not capable of delivering superior performance characteristics that meet or exceed current specifications for the highest quality synthetic base oils.
Bruce Marley is a senior vice president at Biosynthetic Technologies, the company that developed estolides. To find out more about Biosynthetic Technologies and estolides, please visit www.biosynthetic.com.