What type of oil would i use for my 2004 jeep grand cherokee?

The manufacturer generally recommends a 10w-30 oil. That's fine except that after years of research I've found that using a 20w 40 or a full synthetic with the same or better numbers is far better.
Without a long explanation of why, I'll just say that it is far superior as far as being thermally stable and resistant to mechanical shear and contamination while it offers less friction at all moving or sliding internal parts. You can look up noac volitility tests on google for more tech info.
I use synthetics in all my vehicles including race cars and have never had an oil related breakdown ever. My street engines last well over 300 thousand miles!!!
Additives like lucas and marvel oil are good but mostly unnecessary with synthetics. You will likely get a ton of responses on this but my info is proven and valid!!!
Good luck with your Jeep!!