[Dominik]

According to my knowledge, the rings do rotate. But if, or not seems to be secondary. If they stick, they can't rotate - correct. But why did they stick? Was the ring gap to small? Were the rings not plane? Out of round? Or the ring gap out of round?

Has the engine been run too cold? If Roush revvs it high at the dyno and you only cruise at 55 we are looking at vastly different operating conditions, even though the thermostat should balance that out.
However, an aluminium block dissipates heat so much better that you may experience all sorts of heat differentials in the block.

I also agree with Stentor, you should have gotten a new engine right away. Or at least an interim engine to enjoy your car over thanksgiving and christmas.

Dom