HudsonTheStudson

This is my first post as a new member of the forums. I've been reading through posts for a while on here and other sites but never got an account untill today. Anyways, I just bought my first set of wheels, a creampuff of a 97' Cherokee Sport. 94,400 miles. Runs perfect and looks like the mecahnic who owned it before me kept her up. Great truck at any price, especially for only 2400$. Im OCD about things I care about and you better believe this XJ is one of those things. I know and understand the importance of good oil to a vehicle, and I've heard the famous 4.0, since it's a flat tappet, needs a generous amount of Zinc and Phosphorous in its oil. I was curious if this actually is concrete enough to determine oil choice, and if so, how can you tell if an oil meets those requirements? What are some of the high praised oils in that field? Thanks for the help in advance!

theangler

I'm curious about what the others have to say. I use the cheapest 10w-30 I can find year round and I've never had any problems with the I6 4.0L.

Moncheche

Bobistheoilguy.com

You will get a healthy mix of good info and old wives tales when it comes to oil.

Hit the site I posted, read what he has to say, then post back.

I really hate oil threads now.

the buddmang

I switched from using cheap 10w-30 and a purolator filter to using 5w40 Rotella and a Bosch filter and noticed a big difference in the amount of lifter noise I hear at startup and once warm.

Nothing scientific. Did quite a bit of forum research and found some people that tried it and liked it, figured I would try it.

Edit: bobistheoilguy is a GOLDMINE. read it, love it.

HudsonTheStudson

Looking on bobs right now, and I aint finding very specific answers, just mumbojumbo I've heard before. Maybe its because i aint used to the page. and there is just so much info in one place, i dont have a doubt that its there, but where?

djb383

Did u go to Motor Oil University (at BITOG) and start reading Motor Oil 101? After that Google ZDDP myth.

HudsonTheStudson

Perfect! Thats what I was looking for, Straightforward. Thanks.

macgyver35

Until recently, I owned a 2002 wrangler that I bought new. I always used Castrol 10w-30 during the cooler half of the year, and 10w-40 during our extremely hot Texas summers. And I know there are about 500 people on here who will crap themselves when I say this, but I always used Fram filters. I typically went about 5000 miles between changes.

I just sold that Jeep with 145,000 miles on the clock, a lot of those miles around dusty construction sites, and it still runs like new. Super smooth idle, very quiet (no ticking or tapping), and passed it's last emissions test with ease.

Now, I don't know if there are any significant internal changes to the 4.0 between that 02 Wrangler and my 98 Cherokee (I don't think so), but I plan to keep using Castrol. It has a new ATK remanufactured longblock in it that now has about 5000 miles on it. So far so good. I have switched to Mopar filters though, as they are only a dollar more than the Fram, and I didn't want ATK giving me any grief if the motor had any issues during their warranty period.

Radi

Any modern motor oil will protect your cam just fine. If you were running a wild aftermarket cam or high-pressure springs, or were breaking in a new cam I'd have different advice.
But for a stocker that's already broken in- don't lose any sleep over it. Or run Rotella or Delo if you like, both are excellent oils for the 4.0

djb383

Cam has virtually nothing to do with it....it's all about valve spring pressure and the 4.0L has about as much spring pressure as a click type ballpoint pin. LOL

HudsonTheStudson

Ive heard a lot about Shell Rotella Diesel oil for the 4.0. Supposedly it loves it. Anyone care to back this up? And what are the differences between diesel and regular gasoline oils anyways?

HudsonTheStudson

Interesting post. I've never really liked GM's products, but they are one of the big 3. I would expect them to know that. Thanks for pointing it out, but there are still quite a few sources that say otherwise. There has to be some sort of fact behind the assumptions of ZDDP reduction, or they wouldnt have taken root so strongly, would they?

letsgomuddin

A little off topic but ZDDP related. I am a British car mechanic, you know MG's, real Mini's, Jags, Austin Healey's, the whole bit. These cars use a non hydraulic style lifter, and when the oil companies started reducing ZDDP content, we noticed many cam and lifter failures. We have since used a additive that replaces the ZDDP and no longer burn up cams and lifters. Can't just be a coincidence.....can it?

letsgomuddin

And everyone should go to Motor Oil University at Bob is the Oil Guy (http://www.bobistheoilguy.com) This is FANTASTIC information that will explain in great detail what oil rating actually mean and what is best suited for you engine, It will surprise most (including myself) that we need a much thinner oil than we ever thought say around 0W-30. Don't believe me? Read up!

98_XJ Sport

I agree. I am doing an oil change today with Rotella 15w40. When I've used quaker state in the past with some offbrand filter I don't have normal pressure at idle. Rotella seems to pull up my idle pressure and lessen my lifter tick. I know there's a difference between reg. And diesel oils but I can't recall right now