Additional testing was performed using biodiesel produced from soybeans, the leading source of feedstock for biodiesel production in the United States. Because the gelling temperature of soybean-derived biodiesel is much lower than that of tallow-based biodiesel, storage temperatures of 50˚F or higher generally are sufficient.
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(The success of the biodiesel fuel industry relies heavily on biodiesel testing <http://www.youtube.com/watch?v=s32Ke2VzrqU>, not only at the production level but at the consumer level, where degraded fuel may cause engine failures.  Of major concern to diesel and biodiesel users is the very real possibility that water has contaminated their fuel. (See http://www.youtube.com/watch?v=0YcczdvPyAk).  The potential catastrophic impact of this problem is discussed at length  in this video at: http://www.youtube.com/watch?v=-lh4qhXc_5s&feature=youtube_gdata.
Fleet Fuel's  family of inexpensive biodiesel test kits  is just a click away on the internet at:
<http://fleetbiodiesel.com/biodiesel_testing_and_supplies.html>)