The problem with today's bio-based lubricants is that many can't match the cost, oxidative stability, or cold-weather performance of petroleum-based formulations. They're normally made by modifying an edible oil, such as soy oil, to produce desired industrial products like grease or hydraulic fluid. But estolides are different. They're made from only the fatty acid components of high-oleic oils derived from such plants as lesquerella, rapeseed (canola), and sunflower. Researchers produced and tested branched chains of saturated or unsaturated oleic estiolides and found that they performed as well as, or better than, mineral-oil-based lubes.

For example, an unsaturated oleic estolides formulation was still pourable at -22°F, and a saturated one was pourable at -40°F, compared to 0.4°F for a soy-based lube. In a standard oxidative resistance test, the two estolide formulations withstood breakdown for 200 minutes (unsaturated) and 400 minutes (saturated), compared to 200 minutes for the mineral oil used in cars. Now a Cooperative Research and Development Agreement has been signed to explore the creation of canola-based estolides.

Steven C. Cermak, USDA-ARS New Crops and Processing Technology Research Unit, Peoria, Illinois; phone (309) 681-6233.