It's hard to have a "run" on products that would require 500 gal. storage tanks.
Think larger scale, think regionaly, including transportaiton methods, and not locally. Run in this case caused by shortages and human psychology. The region(s) hit try to bid the price up in an effort to get a hold of the product. If it happens over enough time, others will come in and bid it up and try for delievery even store it on ships as we have seen with crude oil in the past. Of course that could then lead to a run, certaily not on 500 gallon tanks, but more like tanker ships and countries who refine it not as likely to sell it. Supplies of crude are tight enough that this could happen with enough time.