I don’t know which white gas you have but here’s something from Coleman’s sight: http://www.coleman.com/coleman/faq/faqreturn.asp?question=19
“An un-opened container of Coleman® Fuel stored in a dry area with no rapid extreme changes in temperature will remain viable for five to seven years. An opened container stored in the same area will remain viable for up to two years though will be at its best if used within a year.

Coleman® Propane Cylinders can be stored indefinitely in a dry area. The propane fuel inside the cylinder will not break down.”

-Barry