I found a test done by credible bio-guys that found that Winterflow 8500 by the Starreon Corp was the most effective.  Here is a link to that post:  http://www.biodieselnow.com/forums/post/29845.aspx  "The untreated B100 had a PP of -2C (28.4F), and 0.1% of additive #2 (winterflow 8500) lowered it to -8C (17.6F). In their tests, the PS DFS additive (#4) that we've been using, lowered the PP by only 2C at 0.1% concentration (to -4C)."

 I can't find that product anywhere, does anyone know where to buy it?  If I have to buy a 55 gallon drum I will however I would like to get a retail quantity if I can, like in quarts, gallons, or 2.5 gallon jugs.  If anyone can help please point me in the correct direction to find this product.  I have found in my searches that starreon was purchased by Octel corp.  Thank you very much for your help and have a great day!  Happy veggieburning!