Spray MMO inside them.
Jim

"Mike Rapoport" wrote in message
ink.net...
I have a Helio Courier with four fuel cells holding 30 gallons each. My
typical flight uses ~35 gallons so I would like to leave the outer (aux)
tanks empty most of the time. I understand that leaving them empty will
reduce their life expectancy. How much should I expect the life
expectancy
to be reduced? It there a proceedure to coat the inside of the bladders
with something that would preserve them? Thanks!

Mike
MU-2