From 50 to 100 degrees. It's my daily driver but I use it to go wheeling as well.

I would run the 5w40 rotella synthetic and change it after 5k if everything looks good after that I may suggest trying 7500 but then it just matters on your air and oil filter. My recommendation is solely what I would do and am sure others may have a opinion.. keep us posted on what you do and how you like the rotella..

should I use rotella on my 01 xj with 90k miles? the weather where I am is chilly in the fall, freezing in the winter months and 80-90s in the summer.

I use Rotella T6 5W-40 and live in western Michigan. Lots of snow & ice, temperature creeping close to 0 or below and it works great.

Thanks if I decide to go with regular Rotella instead of synthetic, is it still the 5w40 I want?

I run rotella 15w-40 in my Honda trx450r and after changing the oil every ten hours it comes out almost brand new. And a gallon jug of rotella around here is $11 so looks like I will be using rotella 10w-30 in my next oil change here shortly

I'm not sure if they make a regular 5W-40, I could be wrong though. 5W-40 is a good all-around weight/viscosity. I highly recommend it. My oil looks as clean as the day I put it in even 5K miles after an oil change. Just make sure you use a good premium filter as well. No FRAM crap.

ive been using rotella 15w-40 in my jeep for about a year and a half, i love it! it makes it run soo smooth and clean too, and since its so thick it stops all the small leaks my motors got, plus its cheap so its more money for a nice oil filter, like an oversized k&n

I personally would not run any other Rotella just because of the Weights offered. I am not a believer in the thicker oils and definitely not a dino higher weight. I would run a 5w-20 synthetic if rotella offered that but since they do not I run RP. Rotella does not make a 5w-40 dino though, just to answer that directly.