What are those of you who operate the Rotax 912 engines seeing for reliability? Has anyone experienced an engine failure? If so, what was the cause?

What about maintenance issues? I have seen some posts about coolant leakage and other things that needed to be addressed, and one person has actually listed the numbers for O rings used in the engines. Am I going to have a box full of O rings in my garage to keep it running? Obviously, no engine will run a lifetime on only oil and gas, but what are you seeing pop up from time to time?

The Rotax Factory video shows the extent of the precision they go to when assembling an engine. Will I be able to perform all maintenance functions without causing other problems because I don't have all the assembly tools they use?

Steve