AH - But Cap'n - the containers for the Ph stuff for your pool is not subjected to ongoing temps of 90-110C plus 20 lbs pressure. I don't know if MBUSA is right (but I think they should know). That is why I asked if any one out there was using MB antifreeze consistently and still had the rad break. If most people reply that they used NA antifreeze and had broken necks - there may something to what they say. Any takers for comments on using MB antifreeze exclusively??