Really? I've always paid right around $20/gallon. For example, it's currently $22.47 at WalMart (I get it online so I don't actually have to set foot in Wally World), and I swear I ordered some a few months ago that was a closer to $21 even.

 

Regular price is $29.99/gal at Advance Auto which is the closest store to me that carries it and every couple of months it goes on sale at $19.99. Last time I needed it, it wasn't on sale and it cost me $77 and change for 2 gallons and a Puralotor One filter!

 

I use T6 in my cummins, so buying another gallon and a half wont hurt.
Question, I only drive 8 miles to and from work in the XJ, and the occasional errand. With my cummins, it takes 10x longer to get to operating temp than my jeep (even if I have the block heater plugged in) and that can be harsh on the oil. Would using T6 in the 4.0 be the same train of thought? I idle the 4.0 in the mornings for about 5 minutes and I'm at operating temp about 5 minutes later.... so I'm assuming I shouldn't worry about T-6 in my 4.0 not getting to temp, right?
On the other hand, with the little amount of driving I do, spending extra $ on oil wont be so bad....
I suppose I can sen my oil off for analysis and see what I'm getting. I should do that anyway since the XJ is new to me.
I always look at all the places that sell oil for who has oil on sale, especially expensive diesel oil.. Autozone, oreilly, advance auto, tractor supply, Murdochs (the local farm supply store) wal-mart, etc....

 

I read the HUGE article about oil in the 4.0........ I cant remember what it said about the valvoline blue (specifically made for Cummins). that's usually cheaper than T-6. Is it a suitable substitute for T-6 in the 4.0? I just cant rtemember what the article said about it... I will use it occasionally in my Cummins if I find a good deal on it...

 

To be honest, I worked at Valvoline Instant Oil Change part time for extra money for over 10 years and have always used Valvoline oil in my vehicles since 1965, including all 3 of my jeeps. I only started using Rotella in my XJ because of the low idle pressure. I'm not totally convinced that ZDDP is that big of a thing as long as the oil you use has a fair amount in it. The one area that it helps is on flat tappet lifters because that's a metal-on-metal high pressure point that needs it. As I previously said, Valvoline Maxlife 10W-30 semi-synthetic has around 600 ppm ZDDP which is enough to do the job on a well broken in engine. I'd probably use a 15W-40 in desert climates.

 

Yup, that's why I just order it online. Oil prices at auto parts stores tend to be much higher than what you pay elsewhere for the same thing.

 

Well, oil does what its supposed to do and if you keep up with your oil changes and use a quality filter, I don't see why needing to use one oil over the other should be a huge issue unless its a specialty motor, like HD Diesel. Or unless it is an absolute must for a certain engine. or it'll blow up or only have half the life its supposed to, like a 15,000 RPM F1 motor or something like that. I would feel fine using valvoline over T6. Or any other quality oil for that matter. I actually watched a video on amazon oil and it performed just as well as the top tier brand oils. Hell, its probably made by mobil1 or valvoline with an amazon sticker slapped on it. Not really sure if I would use amazon oil, but whatever... additives like zinc are great and should be thought about and considered in some motors, and from what I read, obviously its a good thing to use diesel oil in the 4.0, but is there hard data and actually cases that show a motor would have lasted another 100k miles or more if it had T6 in it rather than valvoline gas motor oil in it? Or visual evidence that shows flat tappet parts that used T6 compared to one that used regular oil? I'm not asking to be pretentious, I'm actually curious if there is hard evidence that shows the motor will last SIGNIFICANTLY longer with T6 over gas motor oil....

What about T5? Or T4?

 

Yeah I had that moment of realization when I just recently replaced mine from the ageing and failing OEM one that was 21 years old. Now it reads much more accurately. My OEM one read in the range of the OP there..
but now I'm hot idle around 30-35ish psi and under load 50-55psi with my replacement sensor. And mine is tight with only 107k original on the clock. And after consensus on a thread I put up after I noticed the difference, they all agreed that my replacement one was much more accurate and really what good oil pressure should be on our old 4.0's

 

Getting back to the filter adapter. It is Locktited at the factory assembly and is hard to break loose. It simplest way to remove it is to weld a T60 bit into a 5/8 nut, then use a box wrench and a cheater pipe to break it loose, then put the bit in your toolbox for the future. It doesn't need to be Locktited because it won't loosen up easily without it. There are 3 O-rings to be replaced, industrial numbers are 017, 212,and 230. You can buy a set from a dealer for $15 or $0.75 from a hydraulics shop for all 3. The numbers are different for the older adapters with the external hex on them.

 

I honestly have no idea why people leave the adapter in. If it leaks once, it will leak again.

My previous 4.0 ran 10 years without it and when the engine was pulled for rebuild from the current one, the leaking adapter
was the first thing off as the engine swung out of the engine bay.

I use a 5w-30 for the winter oil and 5w-40 for the summer.
My reading indicates that titanium additives can replace ZDDP.
I've liked the Kendall brand.
Comes cheap enough with Amazon Prime.

 

I ran my XJ without the adapter to see if it made a pressure difference. It didn't change a thing, so I put it back on. Without it, the filter is too close to the motor mount to be comfortable running it that way. An oil cooler should make a big difference in my opinion.