Read several posts from folks that it acted as much as a "super-glue" than as a sealant, including one case where the tank was damaged trying to remove the plug. I asked a tech about it, at the local CW, and he told me that their folks ae all taught to use tape, not goop. Sorry that I can't give a more scientific reason, but it was enough reason for me!
2014 RAM 2500 Laramie 4x4 Quad Cab w/Cummins Turbo Diesel, 2009 Rockwood 2607, and 3 'yaks!
300W of Suntech Solar, a Rogue MPT-3024 Controller, and a Xantrex PW2000 Inverter