I used one bottle, I did not notice any change good or bad, but I don't like having to order it every time I need a bottle so I didn't order anymore. I'm running 2-5% biodiesel now so I'm less concerned about additives, however I do run a cetane booster and injector cleaner every so often. What has been your results with the RBP additive? I didn't see any change in fuel milage or anything.