The Kero is hygroscopic, and it forms seaweed, when I storaged, before use, I use filter separator of particles and water, well, in these conditions, I used kero stored by up to 6 months, one more thing, use clean gallon, I observed minor seaweed formation.
I disassembled turbines with 50 hours without any internal carbonization in the injectors or combustion chamber, but, I use only MOBIL JET II ( recomendation by CARLOS from RTI ).
but, remenber, fresh kero, always better!!!

hope help

jose [8D]