My first question when I read the UP bulletin was why? The o-rings used in the cylinders and valves we use are made out of niltile rubber, also known as NBR or Buna-N. There are different formulations and variations of the material from various suppliers. The reason BVMLube helps fix leaks is because it causes the o-rings to soften and swell slightly. Perhaps someone from UP could explain why it's a problem for them, or what they are doing differently.