From:Robbie e-mail:tls-A-newmex.com
Subject:RE: Drained gas tank Date:Sat Nov 17 19:50:52 2012
Response to:17957
The best thing is a FULLY filled tank as far as protection goes. (gas is oil you know!) Otherwise you are better off leaving the cap off than sealing it. You might even suspend a desiccant pack in it to absorb as much as possible. If sealed the condensation will go to work on it! An unheated garage has enough temperature swing to create lots of condensation. You might need to change jobs. Your boss doesn't get it!

----- ORIGINAL MESSAGE FOLLOWS -----
I've drained the gas tank on the Hummer and it will sit for the next 5 months in an unheated garage (the boss says there's no room in the house).

What do the experts suggest to lessen condensation/corrosion in the tank;
do I leave the gas cap off so air can circulate in tank;
or do I close petcock and put cap on tight?

Thanks.