We are on the third of three six-cylinder Cherokees. The last two (the first of which I have reported extensively here) are both 2WD that get above 22 mpg highway. Both were run on REDLINE oil and BALDWIN B2-HPG filters once I got on board (2002) with the use of LC-20, Fuel Power and ARx.
The last of the two 2001 models needed new 02 sensors at 100,000 miles, the previous never skipped a beat prior to being totalled with about 95,000 miles.
We run about 30,000 miles on RL, then do an ARx clean up using Mobil Delvac 1300 10w30 per Franks instructions (actually, somewhat longer miles in clean and rinse phases) along with the same Baldwin filters.
We also change all other fluids (with RL) at the same interval; the exception being the auto trans where we use SCHAEFFERS ATS.
Schaeffers #221 is used for chassis greasing.