There is currently no additive that I am aware of that lowers the gel point of biodiesel, so any additive is only going to work on the portion of your blend that is petro based.

There is a company called Evonik located near us in SEPA that has products that claim to improve low temp performance of biodiesel.
Biodiesel

We submitted a sample to them in 2009 and they ran some tests which showed no improvement in CFPP and a small improvement in cold storage. What I learned from this was that even though our fuel had a CFPP of 28.7F, if it was kept at higher temps it would start to gel over time. I blend with kerosene and keep a sample in a jar so I know what's going on in my tank. Right now I am at B90 with temps in the lows of 25 and highs of mid 40s for several days and no issues.

here is an email back in 2009 from Evonik:


I've attached a spreadsheet with the low temperature data we've generated so far on your waste vegetable oil methyl ester. We tested various treat rates of our three main Viscoplex biodiesel cold flow improvers, including the samples that you blended, for pour point, cloud point, CFPP, and storage stability. The PP, CP, and CFPP results are located in the first tab of the file. Storage stability w/ pictures is detailed in the second.

For CFPP, we didn't really see any movement with the inclusion of additive. Untreated your B100 measures -3C in the test, and 10-330 can reduce that 2 degrees down to -5C. The other CFIs do not improve (and do not hurt) the result. The -5C value when using 10-330 is right at the test's ~2C variability.

For pour point, we get good improvement using Viscoplex 10-305, brining the pour down from -3C to -27C at 0.5% additive. 10-330 shows activity in pour point too, but does not bring as much improvement.

For cloud point, we see about 1-2C better results when treating with CFI. These results are typical, as our additives do not generally improve cloud point beyond several degrees.

In the storage stability tab, you'll see some pictures and descriptions of samples as we held them at 0C for 7 days. By day 3 the untreated fuel was nearly 50% crystallized, and by day 7 the B100 was essentially solid. The treated samples are cloudy by remain liquid and can readily flow. We're going to drop the temperature down to -5C (23F) and continue monitoring through Friday 11/13.