What oil weight and brand are you running in your 4.0 YJ?

I always recommend Rotella or Dello 10w30 diesel oil. Either one is a good oil at a good price.
Both have sufficient zinc ZDDP to keep your flat tappet cam happy for a long time.
 
After rebuilding my 2.4L I used a 10-30 break-in oil and then switched to Mobil 1 EP. Good oil and can be found on sale. Going with a good filter like WIX is just as important. I write the odometer reading on the filter each time I change them.