Pup and Steve have a much firmer grasp on the chemical aspect of it than I do, but I have to lean towards Jerry on this one.. While I do respect their opinion and knowledge of what cetane enhancers can do to diesel fuel over time, I have a problem with anyone storing fuel for longer than 6mo.. I guess there are situations for some of you guys to stockpile fuel for farms and such, but 6mo supply...??... If I was going to store it for such a period of time, I might go a little deeper and find a better choice for a stabilizer than a PS cetane booster for the reasons mentioned.... But if I had it for 7mo with PS in it, I wouldnt loose any sleep over it /forums/images/graemlins/grin.gif... Like I daid, I dont doubt what these guys are saying, though I relate it to changing your oil at 3000mi vs 6000mi.. The benifits of PS and other fuel system treatments far outweigh the small degredation that they may cause over an extended period of time.. So, I prefer fresh diesel anyhow and am far more concerned about the algae growth and separation ofit over time... Just my opinion, guys...