Oil Questions

[mancilg]

I just recieved my Onstar report and it's telling me that I have 60% of the life left in my oil and I don't need to change it until 11,000 miles. I have 4,000 miles now. That seem to be a long time considering that I have never changed the oil

Questions:
- Does the hummer come synthetic oil?
- If it dosen't come with synthetic is it worth changing over to synthetic?
- If I do chance my own oil, how do I reset the system that reports to onstar?

Thanks guys,
M