SeacretsOceanCity -
Things that make you go "hmm"... I love a good mystery!
Am wondering how the acetic acid in the RTV combines with the fuel and plastic... With no apparent change to the RTV in your tank, maybe it could be a catalyst?
Will advise the status of my RTV-free "control tank" as time goes on... FWIW, am using 15% nitro 18% oil (synthetic and castor mix) Hobbytown USA fuel...
Cheers!
Jim