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.
Oxidative Stability
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.
Volatility
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).
Viscosity Index
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).
Miscibility
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.
Biodegradability
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).
Renewable Carbon
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.
| Base Oil | Percent Renewable Carbon | |
Low Viscosity (5-9 cSt, 100C) | High Viscosity (17-40 cSt, 100C) | |
| Group I | 0 | 0 |
| Group II | 0 | 0 |
| Group III | 0 | 0 |
| Group IV, PAO | 0 | 0 |
| PAG | 0 | 0 |
| Diester | 0 - 30 | - |
| POE | 0 - 75* | 0 - 10 |
| Biosynthetic SE7B | 80 | - |
| Biosynthetic SE20B | - | 90 |
| * Typically < 50% | ||
Bioaccumulation
Per the EPAs definition and according to OECD 117, estolides do not accumulate in living organisms.
Conclusion
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.
