It is my sisters car, and has run on 10w-30 for most of its 90K miles to my knowledge. Car was bought from an old couple and was babied, but not sure of service. Its been garaged for the past 7 months while my sister is in Boston for college. I'm not in the know about these Infiniti engines, but it drives AWESOME and revs to 6000 no problem with the 4.7 liter V8. So what oil?