I am contemplating oil choices for my "new" '01 Cherokee with the 4.0. I have done quite a bit of reading here and it seems the UOAs are a little better for an xw-40 vs. an xw-30. I am an Amsoil user and I was just getting ready to dump some 10w-30 ATM in there with an SDF15, but now I am having second thoughts. I live in a part of western NY where winter lows of -15°F occur almost every year, and morning cold start temperatures of -5°F to 5°F are relatively common. I have been running the 5w-30 ASL in my wife's subaru with excellent results at 7500 mile OCI. I would like to find an xw-40 for the Jeep that I could run all year, if that is both possible and wise. I am not going to use crazy OCIs, so changing for the seasons isn't a problem. Wear, cleanliness, and fuel economy are my priorities in that order. I will be driving about 25k per year.