Does the hummer come synthetic oil?
no If it dosen't come with synthetic is it worth changing over to synthetic? yes
- If I do chance my own oil, how do I reset the system that reports to onstar? I believe its in your owners manual, or call your dealer and ask service . 4000 miles on your new motor isnt very much ,, but its time to get some new oil in her, My first change was at 1200 miles just to get the initial break in oil out and replace with syn. 