spect2k

I found this Toyota oil reference chart when doing some work and reading through some info for my wife's Rav4. I had a number of questions after looking at it that pertain to all cars. It certainly appears that Toyota is moving in the direction of synthetic oils. They have their 3 categories - n, n/s, s.

1) Does something like this exist for Infiniti that anyone has seen?

2) Does anyone know if Infiniti will be transitioning over to synthetics? It just makes so much sense.

3) Why do you think there are certain cars that "require" synthetic, other cars that go either way, and some that are conventional oil only? I'm looking for a technical response here if possible. What would cause an engine to not be able to run on synthetic or vice-versa (not be able to run on conventional)?

Thanks in advance!