Despite the best preventative measures, ruptured hoses, spills and leaks do occur with the use of all hydraulic equipment. Although these releases do not usually produce an RCRA (Resource Conservation and Recovery Act) regulated waste, they are often reportable events. Clean-up and subsequent administrative procedures involve additional costs, labor, and work delays. Concerns about these releases, especially when they involve Sandia National Laboratories, New Mexico (SNL) vehicles hauling waste on public roads, prompted their Fleet Services Department (FS) to seek an alternative to conventional petroleum-based hydraulic fluids.Since 1996, SNL has participated in a pilot program, along with the University of Northern Iowa (UNI) Ag-Based Industrial Lubricants (ABIL) Research Program and selected vehicle manufacturers, to field test in twenty of its vehicles, hydraulic fluid produced from soybean oil. SNL was the largest test user in the pilot program, and collected test samples quarterly from each participating vehicle and sent them to UNI-ABIL. UNI-ABIL and its industrial collaborators then analyzed and evaluated the samples.Other test participants have involved rail-car movers and garbage trucks used by municipalities. In one case, two garbage trucks were fully flushed and filled with soybean-based hydraulic fluid in one, and conventional petroleum in the other. These automated garbage trucks operate 4-days (30 hours) per week, emptying refuse from approximately 1000 containers per day - 1000 complete cycles per day. Rail car movers are run almost continuously, 24 hours per day, although the hydraulic system is used only during the actual rail-car moving activity.Because of the success of the pilot program and subsequent approval of the product for industrial applications, SNL-FS is in the process of converting all hydraulic equipment in its fleet to the soybean product. SNL-FS is also investigating the use of other soybean-based products, including part cleaning solvents and automotive greases.While SNL-FS's activities have been mainly in New Mexico, beginning in December 1995 the rail-car-movers and garbage trucks were operated in Iowa in extreme temperatures of -40°F (run continuously, stored at temperatures above 0°F, or equipped with reservoir heaters) to 100°F. Field test results and analysis of data indicate that despite some apparent shortcomings in laboratory performance, vegetable oils have performed superbly in the field. This has been most evident in the area of pour-point and overall thermal stability.