I checked for specifics on your vehicle. Here is what it indicates:
2003 Infiniti G35 Sedan V6-3.5L (VQ35DE)
Vehicle Steering and Suspension Steering Power Steering Power Steering Fluid Specifications Fluid Types
Genuine NISSAN PSF or equivalent
Basically, get basic power steering fluid. Just read the container and confirm it works in Nissan / Infinity vehicles. There really isn't anything out of the ordinary with it.
Let me know if you have other questions.
Monday, January 13th, 2020 AT 8:53 PM