I was wondering what is the best oil to run in my 2000 XJ 4.0L with 186xxx miles. I have been running Mobil 1 10w30 and Lucas Oil every 3,000 miles. Is there anything better, stuff to stay away from?

 

I run just Mobil 1 10w30 but this next change I think I am gonna run royal purple and the lucas oil. Now that you run a full synethic oil dont switch back to regular oil just stay with synethics and u will be fine.

 

Just keep doing what you are doing. Mobil 1 is good oil so you should be ok. It's not good to change oil brands and types all the time. Start with one and just stick with it. The only brands I would personally stay away from is Quaker State and Penzoil other then that should be ok with Mobile, Valvoline, Castrol GTX and so on.

 

I'd say running Mobil 1 synthetic and Lucas Oil, that you are doing everything you can to get the most life out of it.

 

I agree with all. Stay with what you have been doing.

 

I've been running Mobil 1 In my XJ sense it had 6,000 on the clock. I change oil and rotate my tires every 6K in all my Vehicles. Now my XJ has 135k and still going. I have Mobil 1 in my Tahoe, Chevelle, and wifes Cobalt SS S/C. I changed out the oil pan gasket on my XJ last summer. No slug, Very very clean.

 

Also I run a Mobil 1 filter in my XJ. I can still read through the oil before I drain it. I just use the ACDelco in my others, they don't see the dust that my XJ does. They are also $13 a pop.

 

I use castrol gtx 10w40 with a bottle of lucas and mobile 1 filter.. i have 228k miles. I don't want to switch to synthetic because I heard I'll leak like crazy..

 

I have also heard of using Rotella Diesel oil 15w40 or 5w40.

 

I run amsoil 10w-40 full syn. I used to run Castrol Syntec blend. As for full syn you can buy pretty much anywhere, Pennzoil Platinum (full syn) and Valvoline SynPower (full syn) are some of the best. The Valovoline has zinc additive in it also (something that our Jeeps need).

Side note, I hate pennzoil, but their full syn has proven itself quite well.

 

The only reason you may have a leak with synthetic oils is because they clean all the sludge out. So where you had a leak at one time the cleaning properties of the synthetics will open it up. They don't start new leaks.