Your the type of person that the Oil companies love to see.

The owners manual recommends 4k miles for A and 5k miles for B conditions.
Synthetics have come along ways in the last twenty or so years since our Jeeps was new. So expecting a change interval of 7 to 9k miles for ful synthetic is not out of the question.
To each their own. Do yourself a favor and pull an oil sample at 3k miles and have it analyzed.

 

Valvoline max life high mileage 10w-30.....I've been using the brand for the past 100,000 miles or so in my motor and trans. 268,000 miles with no issues.

 

I think im gonna stick with the 10w30. I bought a new sender ($35) that I don't need & never installed after I went back to 10w30 with no issues... Guess I have a backup now... lol

 

I don't change at 4k it because I think it's going to break down, I change it at 4k because it keeps the engine clean. You can very easily tell when an engine hasn't had its oil changed when it should.

 

X2 on the Toooo sooon oil changes with Synthetic. Of course it Matters what type of Synthetic You are Usung. The Only Grade of Castrol Syntec that should be used in Our beloved 4.0s is their European Spec 0w-30(Made in Germany ONLY) and 5w-40(Made In Belguim or U.S.) ALL other grades of Castrol Syntec Are NOT true Synthetics,.Ie Group 4 or Group 5. They are Group 3, which is a Severly HydroCracked Petro Oil. Its very pure petro(dinosaur) oil, but still Dinosaur oil vs a Group 4 oils base of PolyAlphaOlefins or Group 5s base oil of Esters cant compete. I personally think Our Gud Ol Ancient Technologly 4.0s like Dino oil. I just put Quaker State GREEN bottle 10w-40 in my Beloved 2001, and Its gonna get Pounded.

 

MC5000 and Kendall t1 Semi Synthetic (BITOG people love the Kendall)
5w30 winter 10w30 summer (maybe 40wt once it gets into the 80s)

 

10W-30 Valvoline Full Synthetic year round. It seems to be holding up well and my jeep dosent seem to complain and Im taking them up on there 300,000 mile guarintee.

 

I run castrol GTX High Mileage 10w-30 all year round.