If you have a 4.0, I wouldn't stress to much about oil...
I completely rebuilt my jeep over a 3 month period and forgot I drained the oil to change the oil pan gasket since it was the first of many things I did. I ran it for a good 20 minutes while bleeding the breaks before the motor stalled. Once I put oil in (Advanced auto cheap crap) and it fired back up and ran mint. 15,000 miles later She pur's like a kitten still with Amsoil 10w-40. My old cherokee beater I ran it for 65,000 miles and changed the oil every 10,000 miles with advanced auto oil. It was a beater I bought for 300 bucks so I just wanted to push the limits. I sold it without a knock, just the ever popular 4.0 wrap/tick.