To actually answer your first question. I treat year around for cetane and anti gel because I don't always fill my bulk tank in the fall. All depends on my usage. It can get in single digits to below zero here in winter. I want that added pop of extra cetane and no gelled fuel. By dosing year around I'm covered. Same with fuel stabilizer. I put it in every can I fill even knowing much will be used long b4 the stabilizer will be needed. But, I don't have to wonder if that fuel setting there over winter is stabilized or not because I know it is.