Picked up a 2001 Cherokee XJ 60th Anniversary Ed. for a winter car/light off road/something relatively easy to work on and cheap parts etc. 157k on the odometer My question is this - as soon as I got it I drained what was in it and put in standard MS5K 10w30 - just to know I had new oil at least. Would there be anything wrong with running this oil full time? I see a lot about PYB in these engines as well as Rotella T5 but they are more costly, and I want costs low as this is a second car. Definitely M1 does not seem to be a popular choice for people, high iron etc, and that's all I've been running in my Audi so I can't exactly just stick to what I know. I've searched for a UOA on MS5K but no luck, maybe I'm not good enough with searching. Also a question on OCI, manual seems to say 7500mi but I don't see many running that on their Jeeps, is there a reason for this? I don't mind to change more often but of course less is less waste, less hassle if there's no good reason to do more. The jeep will be driven on short/med trips in the mountains with a long (3-6hr) trip every week or two most likely. We do have a winter here in Boone with snow and somewhat cold temps, wondering if I should switch to 5w30 for that season? Seems people are split on that topic. Hoping this Jeep lasts so I can trade my A3 hatch for a RWD coupe at some point and just rely on the Jeep when I need more utility - I'm definitely trying to do my part to keep it on the road so any help will be appreciated.