I fixed this car engine leak in May this year (2011) and it's holding up very well - it would have leaked by now if it was going to, so it's good stuff! It has to put up with temperatures of about 80C (well within sugru's range) but it also has to deal with the pressure that builds up in these cooling systems. Sugru is also preventing a leak from a missing bolt from causing problems too. Well done, another great Irish product! David, Ireland.