Found kerosene at Hess in hampton nh on rt. 1, 4.33/gal. I got Power Service Diesel Fuel Supplement at Autozone. It says it works for b20 and lowers the gell point 30 degs. Power Service also makes a biocide to prevent spoiling. They also make Arctic Express® Biodiesel Antigel, which is specifically made for biodiesel.

The generall rule is:

B100 from April 1 to Oct 15. B50 from Oct 15 to Dec 1st and all of March. B20 only from December thru February.

I will probably try to push this limit by cutting with kerosene and using additives. I still need to research additives more and try to find the best. I am sure somebody has tested these. Anybody?