What is the best oil for my 1997 Jeep Wrangler TJ 4.0?

I use rotella 10w-30 with mopar filter.

Dont worry though, the 4.0 is not picky. Just put in whatever cheap 10w-30 you can buy and it'll be happy.
 
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Motor oil. Whatever you prefer is fine. Use the right viscosity for your location, but brand is not critical. Personally I like Valvoline. Has one of the best additive packages of any brand. If you have high milage or are concerned about wear then add 1/2 qt of diesel oil when changing fluid/filter. It has a lot more zinc for cam and lifters. New oil specs have changed from years ago lowering the zinc level required for newer engines.
 
There is no "best oil" for your Jeep.

As long as you run the right oil weight, you can put any oil in it you want and it's not going to make any difference whatsoever, period.
 
Chris said:
There is no "best oil" for your Jeep.

As long as you run the right oil weight, you can put any oil in it you want and it's not going to make any difference whatsoever, period.
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I am going to have to respectfully disagree with the last part
 
From the owner's manual (2004)

IMG_0221 (2).jpg
 
I returned the Rotella T6 I had in the garage and bought Valvoline Full Synthetic High Mileage with Maxlife technology based on this:

https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/
I've since joined the camp that believe zinc concentration is meaningless, and instead concern myself with film strength, which is a measurement of the oils ability to stay put instead of being squeezed out between the cam lobe and lifter face surfaces. Gasoline engine oils seem to fall mostly from the 80-120kpsi range, while most Rotella (and diesel oils in general) are bottom of the barrel in this metric at 70k and below.

It probably matters on high-revving race engines, but will it amount to a hill of beans for a 20 year old 4.0? Probably not, but the valvoline I bought was the same price so a little extra peace of mind isn't costing me a dime.
 
I've changed the oil once so far on my LJ and I probably did it before it was due but I didn't know what the previous previous owner put in there or at what mileage (all I had was a window sticker saying when it was due).

I used Mobil 1 High Mileage 10W-30 and the Mobil 1 long life filter (M1-204A).
 
While we're on this subject, is there a larger oil filter than what's specified? Plenty of room, might as well use a larger filter.
 
Mine had an engine replacement 2 PO's ago and supposedly they recommended Mobil 5W 30 synthetic so that's what it's been running since the engine swap in 2015. It was in Florida and Virginia, nowhere really cold so I don't know why the 5W was preferred over the 10W.
 
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