Anyone who wants to keep their engine running past 150,000 miles should change it every 5,000 miles using synthetic oil 3000 miles using conventional oil. These hemi's have small passage way's that will get clogged if you don't follow this. Even one miss (going 10K) could put you in jeopardy. I know that from experience. I also do an engine flush every 50,000, every other oil change (on the 10's) I add a half a quart of MMO in 2 to 300 miles before the change (you could also use seafoam) I have trucks with over 400,000 miles on them, so I believe changing the oil is the secrete. We drive them hard and the only things we maintain are the oil changes at 5k trans fluid change every 80K rear diff every 50k. Only weak link has been the rear end gears getting chewed. Take it for what it's worth. I prefer Castorl Edge, but any synthetic oil should be fine.