Thanks. Curious how it'll do.

 

Should be fine if you already run a 40 grade oil. Some 4.0s don't respond well, to which I say just run whatever makes the engine happy.

 

Prior owners ran 5-30. But maybe that extra bit wouls help my valve noises. Only has 125k and sounds like a tractor

 

It basically is one, lol. I'l bet more of them sound like that than don't once they get some miles on them. And it'll clack clack clack it's way to 200K, then 300K...

 

If I see anywhere close to 300k on this jeep ill be pretty happy.
Gonna try rotella next paycheck and see what she thinks

 

Using a lower viscosity is better than a higher viscosity.

 

4.0s love Rotella 15-40 T3 diesel oil.

 

Generally yes, certainly for startup viscosity, but I really have no idea why you think running a 20-grade oil is appropriate in an engine where 40s were specified. Have you ever had a UOA done to see how much iron you're shedding? The best UOAs in 4.0s are with Rotella T6 and Delvac 1 5w40...

 

I was skeptical about the 4.0 loving 15w40 Rotella. I switched to it a few weeks ago because it's what I use at work (free to me if I don't get cought), and I can honestly say that the 4.0 does seem to run better with the Rotella.

 

Everybody wants to make oil selection so complicated for a 4.0. Rotella and Wix. Go together like peas and carrots.

 

Agreed

 

Don't you have the power to close this thread. Question has been answered already. Rotella. Nuff said. If you worried about going thick use t5 10-30. As for filters I like mopar, wix or napa gold. I have better oil pressure with my rotella setup now than I did with Mobil 1 oil and filter.

 

Yeah, I do. But another will crop up in it's place........

 

:sigh: so true. Too bad a requirement of the site isn't to learn how to search before you get a username.

 

roflmao!!

Like an entry exam. Must know how to recognize the word "search".

Reminds me of an old joke. A guy in a spelling contest is asked how to spell "farm". The emcee uses the word in a sentence for the contestant. "Old MacDonad had a farm".

Contestant replies "E*I*E*I*O"