Oil recomendation - Jeep Grand Cherokee 4.0L

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1. What kind of vehicle you have

1997 Grand Cherokee 4.0L I-6


2. What your owner's manual says -- not just viscosity, but certifications (look for acronyms like API SM, ILSAC GF-4, etc.) and change intervals as well

I don't have a owners manual. I know that Jeep calls for a 10w-30 oil



3. Where you live

High desert, SoCal. 2500 ft level. 114f summers to 20f winters at the extremes.



4. How you drive (easy? hard? fast? slow?)

Drive easy, floored to get on freeway, Italian tuneup day before oil changes. Off road easy, trail runs, mild rock crawling a few times a year.




5. What your daily drive is like (short trips? long trips? city? highway?)

Commute twice weekly from 2500 ft level to 4200 ft level then down to 800ft level and then back. Otherwise it's mild city driving the rest of the week.




6. Whether your car has any known problems

No know problems. Doesn't burn a lick of oil during a regular 3000 mile Oil change interval.





If you have any preferences -- synthetic vs. conventional, store-bought vs. ordered online, how long you'd like to go between oil changes, etc. -- or any other info you think might be important, let us know that as well.



No preference, other than what will help to get me past the 300,000 mile mark.

Here's the deal. I bought my 1997 Jeep Grand Cherokee with 197,000 miles on it. I now have 214,000 miles on it.
Previous owner was anal about regular maintenance, oil changes regularly. I have done the same. Oil changes between 3000-5000 mile.
I bought into the "use a heavier oil, Jeep 4.0L engines like it" and used a generic 15w-40 from my past job(major forklift manufacturer branded oil). for first two changes. Then switched to Rotella 15w-40 for the last few changes, due to the "you need zinc in Jeeps" ideas out there.
The last oil change I switched up, went with Pennzoil Yellow Bottle dino oil in a 5W-20 weight. Here's why.
I read a paper about using the lowest viscosity oil that still maintains proper oil pressures. Engines run up to a regular temperature, regardless of outside temp. My engine runs right between 200-210F, regardless of outside temps. The lower initial viscosity will help to get the oil flowing quicker and reduce that "startup wear" that is supposed to be the bigger killer. My engine has always been 20-30PSI at idle up to about 1500 rpm, then 40+ PSI after any RPM above 1500RPM. So I was good for pressure.
As a forklift tech, I understood that the flow is most important, to a point, over pressure. Maintain pressure and flow, your golden. But then further reading, oil shear under loads, Jeep cams grinding themselves up, needing zinc, others say once broken in your golden and on. Now my head is spinning.
One last note, I don't tow or drive heavily loaded. I do understand that if I did so, I'd want the heavier oil to handle the increase loads, temp and others, when doing so.

So, with all that, what do you think? Is it hype about needing zinc for the entire life of a Jeep 4.0L engine? Am I good with a 5w-20? Should I move to a 5w-30, go to factory recommended 10w-30?

Again goal is, 300,000+life on this engine.

Oh, one last note, the "diesel" tick the engine has had while using 15w-40 went away when I switched to 5w-20, I liked that. It has slightly returned now that I'm at the 3000 mile mark on this load of 5w-20. Normal?

Thanks for your time and answers, I'll make sure to stop in to answer any questions posed.

Other than that, I hate this site. It has sucked me in and I have lost DAYS reading through the boards. Still left with my head spinning! LOL.
 
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In my old ZJ 4.0, I ran PYB 5W-30 which it seemed to love. I ran a synthetic once, but it drasticappy increased the leak I had at the oil filter adapter. Switched back to PYB and it slowed way back down.
 
PYB 10W30 has worked well in my 01. Magnatec, Maxlife, and MS5K have run totally fine as well. I've treated it to PP 10w30 once and it did feel nice, but it's probably overkill for it.
 
Howdy neighbor! How you liking this heat and humidity! I was in Ontario yesterday, 115F there, WOW!

Anyways, neither of you are concerned with the zinc/cam details and the removal of zinc?

Fixed my oil filter adapter leak right after buying it. Right now I have a small leak on the left side of the oil pan gasket seam. I'll fix that next oil change, drop the pan and have a looky inside. Have had the valve cover off, clean as a whistle. Oil on dipstick is still semi clear, even so close to 3000miles on this oil. Swapped in a 99+ intake, intake runners were spotless! I've always ran Costco gas with Techron every oil change. So far extremely happy with this Jeep. I want to make it last.
 
Originally Posted By: RJCannon
Howdy neighbor! How you liking this heat and humidity! I was in Ontario yesterday, 115F there, WOW!

Anyways, neither of you are concerned with the zinc/cam details and the removal of zinc?

Fixed my oil filter adapter leak right after buying it. Right now I have a small leak on the left side of the oil pan gasket seam. I'll fix that next oil change, drop the pan and have a looky inside. Have had the valve cover off, clean as a whistle. Oil on dipstick is still semi clear, even so close to 3000miles on this oil. Swapped in a 99+ intake, intake runners were spotless! I've always ran Costco gas with Techron every oil change. So far extremely happy with this Jeep. I want to make it last.
check the oil pan bolts nearest the exhaust pipes. Those seem to loosen up and tightning them often works.
 
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The Jeep 4.0L is a popular oil post on here.

Use a 10w30. Doesn't really matter what brand, they aren't picky as far as brand. The 4.0L is known to shear oil down a grade, which you don't want to do, don't run a 5w20. Oil isn't going to get anywhere any faster from one grade to the next unless you're at -20 degrees.

Here's a list of oils I've run in my Jeep:
Dealer bulk
Castrol GTX HM
Valvoline Maxlife
Chevron Supreme HM
Pennzoil Platinum
Mobil 1 HM
Napa Conventional

It runs the same on all of them. Pick a 10w30 and go for it. I'd do 3-4,000 on conventional and 5-6,000 on synthetic. And yes you can switch from conventional to synthetic and back as much as you'd like.
 
Originally Posted By: Dave9
Formatting, I didn't read that.


Hey, thanks for the helpful input!

Now where's that thumbs up/smilie thingy?
 
Originally Posted By: Chris142
check the oil pan bolts nearest the exhaust pipes. Those seem to loosen up and tightning them often works.


The simple things. I didn't even think to check 'em when I've been under there. Gonna do it tomorrow.

Thanks!!
 
Originally Posted By: Nick1994
The Jeep 4.0L is a popular oil post on here.

Use a 10w30. Doesn't really matter what brand, they aren't picky as far as brand. The 4.0L is known to shear oil down a grade, which you don't want to do, don't run a 5w20. Oil isn't going to get anywhere any faster from one grade to the next unless you're at -20 degrees.

Here's a list of oils I've run in my Jeep:
Dealer bulk
Castrol GTX HM
Valvoline Maxlife
Chevron Supreme HM
Pennzoil Platinum
Mobil 1 HM
Napa Conventional

It runs the same on all of them. Pick a 10w30 and go for it. I'd do 3-4,000 on conventional and 5-6,000 on synthetic. And yes you can switch from conventional to synthetic and back as much as you'd like.


Yeah, I was figuring going back to the 10w-30.

No issues with cams with less zinc? Should I just stop over thinking and just go with the flow huh?

Like I said above, looking for 300k+ miles...
 
The valve springs aren't that strong, so no big need for high zinc as in high strength spring set-ups.
 
You could easily run 5k changes. I would stay with the 15-40 or a 10-30. If you can find a 10-30 that is not labeled resource conserving it will be on the thicker end. I'd recommend M1 HM 10W-30 because it's almost a 40 but it's way overkill for 3k
 
My Jeep's mileage is just under yours. Noise wise, I think it prefers something xxw40 now as it's pretty clackity (your diesel ticking) on anything else. I ran 10w30 and 5w40 for the longest time before this issue and noise free for the most part.

Now I am running Castrol Edge HM 10w40. It's a slight overkill for this engine, but it seems to run just as quiet on this as it does with PYB.

I would not run 5w20 in an engine requiring a 10w30. Mine seems to be picky with oil filters so that may be a cause for the ticking you're experiencing too.
 
Run a quality 10W30 oil. Synthetic if you have the extra $$.

Don't over think it. The engine is not that picky.

Be more concerned with #331 head cracking or piston skirt cracking and falling off.
 
Originally Posted By: Donald
Run a quality 10W30 oil. Synthetic if you have the extra $$.

Don't over think it. The engine is not that picky.

Be more concerned with #331 head cracking or piston skirt cracking and falling off.


The head cracking issue was for years 99-01. (The year you had.) Somewhat simple fix and not the end of the world by any means. Torn piston skirts were about this era too..

He'll see 300k no problem.
 
Perfect oil for your 4.0 if it were mine I would run Chevron Delo XLE 10w30 it's a diesel oil that has a SN rating for gas motors and is real shear stable and it's real reasonable avail at WM.
 
Took care of 2 of these engines (one in a 1988 another in a 1999) over a 15 year run.

I used what was on sale.

White bottle "Formula Shell 10W-30" from Costco made them the happiest. Quiet oil loved by many.
 
I've got two '96 Cherokees and a '98 Grand Cherokee, all with the 4.0/6. One of my '96 Jeeps is closing in on 300K miles.
Here, it can get to be 110° in the summer or -20° in the winter.
I use 5W-30 or 10W-30. Brand is not important.
I normally using the oil filter that the catalog calls for, but on occasion I've used the PH8A-sized oil filter.
Don't overthink the oil for a 4.0 Jeep engine.
 
I read a paper about using the lowest viscosity oil that still maintains proper oil pressures. Engines run up to a regular temperature, regardless of outside temp. My engine runs right between 200-210F, regardless of outside temps. The lower initial viscosity will help to get the oil flowing quicker and reduce that "startup wear" that is supposed to be the bigger killer.

There are similar statements around the internet. 5w-20, 5w-30, 0/5w-40 oils will all flow about the same on startup in your climate...and probably even the 10/15w's as well. And the differences in flow between a 5w-20 vs. 10w-30 in your climate is negligible on startup. There is an advantage to thicker oils on startup as long as they will pump and flow adequately...as they give the initial protection for those seconds while you oil flow is being reestablished. I'd recommend reading the New Motor Oil University articles on this site.

Motor Oil University
 
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